Refactor LevelDbFileBuilder to accept DS Entity (#599)

* Refactor LevelDbFileBuilder to accept DS Entity

Builder now can directly work with Datastore Entity objects.
No need to wrap data in ComparableEntity.

build.gradle

@@ -197,6 +197,10 @@ task runPresubmits(type: Exec) {
   args('config/presubmits.py')
 }
 
+def javadocSource = []
+def javadocClasspath = []
+def javadocDependentTasks = []
+
 subprojects {
   // Skip no-op project
   if (project.name == 'services') return
@@ -317,6 +321,10 @@ subprojects {
       }
     }
   }
+
+  javadocSource << project.sourceSets.main.allJava
+  javadocClasspath << project.sourceSets.main.compileClasspath
+  javadocDependentTasks << project.tasks.compileJava
 }
 
 // If "-P verboseTestOutput=true" is passed in, configure all subprojects to dump all of their
@@ -445,3 +453,18 @@ task javaIncrementalFormatApply {
 }
 
 tasks.build.dependsOn(tasks.javaIncrementalFormatCheck)
+
+task javadoc(type: Javadoc) {
+  source javadocSource
+  classpath = files(javadocClasspath)
+  destinationDir = file("${buildDir}/docs/javadoc")
+  // In a lot of places we don't write @return so suppress warnings about that.
+  options.addBooleanOption('Xdoclint:all,-missing', true)
+  options.addBooleanOption("-allow-script-in-comments",true)
+  options.tags = ["type:a:Generic Type",
+                  "error:a:Expected Error"]
+}
+
+tasks.build.dependsOn(tasks.javadoc)
+
+javadocDependentTasks.each { tasks.javadoc.shouldRunAfter(it) }

common/src/main/java/google/registry/util/Sleeper.java

@@ -21,7 +21,6 @@ import org.joda.time.ReadableDuration;
  * An object which accepts requests to put the current thread to sleep.
  *
  * @see SystemSleeper
- * @see google.registry.testing.FakeSleeper
  */
 @ThreadSafe
 public interface Sleeper {

config/presubmits.py

@@ -99,6 +99,15 @@ PRESUBMITS = {
         "System.(out|err).println is only allowed in tools/ packages. Please "
         "use a logger instead.",
 
+    # ObjectifyService.register is restricted to main/ or AppEngineRule.
+    PresubmitCheck(
+        r".*\bObjectifyService\.register", "java", {
+            "/build/", "/generated/", "node_modules/", "src/main/",
+            "AppEngineRule.java"
+        }):
+      "ObjectifyService.register is not allowed in tests. Please use "
+      "AppengineRule.register instead.",
+
     # PostgreSQLContainer instantiation must specify docker tag
     PresubmitCheck(
         r"[\s\S]*new\s+PostgreSQLContainer(<[\s\S]*>)?\(\s*\)[\s\S]*",

core/build.gradle

@@ -295,6 +295,8 @@ dependencies {
   testAnnotationProcessor deps['com.google.auto.value:auto-value']
   annotationProcessor deps['com.google.dagger:dagger-compiler']
   testAnnotationProcessor deps['com.google.dagger:dagger-compiler']
+  annotationProcessor project(':processor')
+  testAnnotationProcessor project(':processor')
 
   testCompile deps['com.google.appengine:appengine-testing']
   testCompile deps['com.google.guava:guava-testlib']
@@ -707,7 +709,10 @@ task outcastTest(type: FilteringTest) {
   tests = outcastTestPatterns
 
   // Sets the maximum number of test executors that may exist at the same time.
-  maxParallelForks 5
+  // Note that this number appears to contribute to NoClassDefFoundError
+  // exceptions on certain machines and distros. The root cause is unclear.
+  // Try reducing this number if you experience similar problems.
+  maxParallelForks 3
 }
 
 // Whitebox test verifying that RegistryTool can be instantiated. Note the
@@ -875,6 +880,9 @@ task standardTest(type: FilteringTest) {
   // forkEvery 1
 
   // Sets the maximum number of test executors that may exist at the same time.
+  // Also, Gradle executes tests in 1 thread and some of our test infrastructures
+  // depend on that, e.g. DualDatabaseTestInvocationContextProvider injects
+  // different implementation of TransactionManager into TransactionManagerFactory.
   maxParallelForks 5
 
   systemProperty 'test.projectRoot', rootProject.projectRootDir

core/gradle/dependency-locks/annotationProcessor.lockfile

@@ -12,24 +12,24 @@ com.google.dagger:dagger-producers:2.21
 com.google.dagger:dagger-spi:2.21
 com.google.dagger:dagger:2.21
 com.google.errorprone:error_prone_annotation:2.3.3
-com.google.errorprone:error_prone_annotations:2.3.3
+com.google.errorprone:error_prone_annotations:2.3.4
 com.google.errorprone:error_prone_check_api:2.3.3
 com.google.errorprone:error_prone_core:2.3.3
 com.google.errorprone:error_prone_type_annotations:2.3.3
 com.google.errorprone:javac-shaded:9-dev-r4023-3
 com.google.googlejavaformat:google-java-format:1.5
 com.google.guava:failureaccess:1.0.1
-com.google.guava:guava:27.0.1-jre
+com.google.guava:guava:28.2-jre
 com.google.guava:listenablefuture:9999.0-empty-to-avoid-conflict-with-guava
-com.google.j2objc:j2objc-annotations:1.1
+com.google.j2objc:j2objc-annotations:1.3
 com.google.protobuf:protobuf-java:3.4.0
 com.googlecode.java-diff-utils:diffutils:1.3.0
-com.squareup:javapoet:1.11.1
+com.squareup:javapoet:1.12.1
 javax.annotation:jsr250-api:1.0
 javax.inject:javax.inject:1
+javax.persistence:javax.persistence-api:2.2
 org.checkerframework:checker-compat-qual:2.5.3
-org.checkerframework:checker-qual:2.5.3
+org.checkerframework:checker-qual:2.10.0
 org.checkerframework:dataflow:2.5.3
 org.checkerframework:javacutil:2.5.3
-org.codehaus.mojo:animal-sniffer-annotations:1.17
 org.pcollections:pcollections:2.1.2

core/gradle/dependency-locks/testAnnotationProcessor.lockfile

@@ -12,24 +12,24 @@ com.google.dagger:dagger-producers:2.21
 com.google.dagger:dagger-spi:2.21
 com.google.dagger:dagger:2.21
 com.google.errorprone:error_prone_annotation:2.3.3
-com.google.errorprone:error_prone_annotations:2.3.3
+com.google.errorprone:error_prone_annotations:2.3.4
 com.google.errorprone:error_prone_check_api:2.3.3
 com.google.errorprone:error_prone_core:2.3.3
 com.google.errorprone:error_prone_type_annotations:2.3.3
 com.google.errorprone:javac-shaded:9-dev-r4023-3
 com.google.googlejavaformat:google-java-format:1.5
 com.google.guava:failureaccess:1.0.1
-com.google.guava:guava:27.0.1-jre
+com.google.guava:guava:28.2-jre
 com.google.guava:listenablefuture:9999.0-empty-to-avoid-conflict-with-guava
-com.google.j2objc:j2objc-annotations:1.1
+com.google.j2objc:j2objc-annotations:1.3
 com.google.protobuf:protobuf-java:3.4.0
 com.googlecode.java-diff-utils:diffutils:1.3.0
-com.squareup:javapoet:1.11.1
+com.squareup:javapoet:1.12.1
 javax.annotation:jsr250-api:1.0
 javax.inject:javax.inject:1
+javax.persistence:javax.persistence-api:2.2
 org.checkerframework:checker-compat-qual:2.5.3
-org.checkerframework:checker-qual:2.5.3
+org.checkerframework:checker-qual:2.10.0
 org.checkerframework:dataflow:2.5.3
 org.checkerframework:javacutil:2.5.3
-org.codehaus.mojo:animal-sniffer-annotations:1.17
 org.pcollections:pcollections:2.1.2

core/src/main/java/google/registry/batch/DeleteContactsAndHostsAction.java

@@ -283,7 +283,9 @@ public class DeleteContactsAndHostsAction implements Runnable {
     /** Determine whether the target resource is a linked resource on the domain. */
     private boolean isLinked(DomainBase domain, Key<? extends EppResource> resourceKey) {
       if (resourceKey.getKind().equals(KIND_CONTACT)) {
-        return domain.getReferencedContacts().contains(resourceKey);
+        return domain
+            .getReferencedContacts()
+            .contains(VKey.createOfy(ContactResource.class, (Key<ContactResource>) resourceKey));
       } else if (resourceKey.getKind().equals(KIND_HOST)) {
         return domain
             .getNameservers()

core/src/main/java/google/registry/batch/ExpandRecurringBillingEventsAction.java

@@ -155,89 +155,100 @@ public class ExpandRecurringBillingEventsAction implements Runnable {
       }
       int numBillingEventsSaved = 0;
       try {
-        numBillingEventsSaved = tm().transactNew(() -> {
-          ImmutableSet.Builder<OneTime> syntheticOneTimesBuilder =
-              new ImmutableSet.Builder<>();
-          final Registry tld = Registry.get(getTldFromDomainName(recurring.getTargetId()));
+        numBillingEventsSaved =
+            tm().transactNew(
+                    () -> {
+                      ImmutableSet.Builder<OneTime> syntheticOneTimesBuilder =
+                          new ImmutableSet.Builder<>();
+                      final Registry tld =
+                          Registry.get(getTldFromDomainName(recurring.getTargetId()));
 
-          // Determine the complete set of times at which this recurring event should occur
-          // (up to and including the runtime of the mapreduce).
-          Iterable<DateTime> eventTimes =
-              recurring.getRecurrenceTimeOfYear().getInstancesInRange(Range.closed(
-                  recurring.getEventTime(),
-                  earliestOf(recurring.getRecurrenceEndTime(), executeTime)));
+                      // Determine the complete set of times at which this recurring event should
+                      // occur (up to and including the runtime of the mapreduce).
+                      Iterable<DateTime> eventTimes =
+                          recurring
+                              .getRecurrenceTimeOfYear()
+                              .getInstancesInRange(
+                                  Range.closed(
+                                      recurring.getEventTime(),
+                                      earliestOf(recurring.getRecurrenceEndTime(), executeTime)));
 
-          // Convert these event times to billing times
-          final ImmutableSet<DateTime> billingTimes =
-              getBillingTimesInScope(eventTimes, cursorTime, executeTime, tld);
+                      // Convert these event times to billing times
+                      final ImmutableSet<DateTime> billingTimes =
+                          getBillingTimesInScope(eventTimes, cursorTime, executeTime, tld);
 
-          Key<? extends EppResource> domainKey = recurring.getParentKey().getParent();
-          Iterable<OneTime> oneTimesForDomain =
-              ofy().load().type(OneTime.class).ancestor(domainKey);
+                      Key<? extends EppResource> domainKey = recurring.getParentKey().getParent();
+                      Iterable<OneTime> oneTimesForDomain =
+                          ofy().load().type(OneTime.class).ancestor(domainKey);
 
-          // Determine the billing times that already have OneTime events persisted.
-          ImmutableSet<DateTime> existingBillingTimes =
-              getExistingBillingTimes(oneTimesForDomain, recurring);
+                      // Determine the billing times that already have OneTime events persisted.
+                      ImmutableSet<DateTime> existingBillingTimes =
+                          getExistingBillingTimes(oneTimesForDomain, recurring);
 
-          ImmutableSet.Builder<HistoryEntry> historyEntriesBuilder =
-              new ImmutableSet.Builder<>();
-          // Create synthetic OneTime events for all billing times that do not yet have an event
-          // persisted.
-          for (DateTime billingTime : difference(billingTimes, existingBillingTimes)) {
-            // Construct a new HistoryEntry that parents over the OneTime
-            HistoryEntry historyEntry = new HistoryEntry.Builder()
-                .setBySuperuser(false)
-                .setClientId(recurring.getClientId())
-                .setModificationTime(tm().getTransactionTime())
-                .setParent(domainKey)
-                .setPeriod(Period.create(1, YEARS))
-                .setReason("Domain autorenewal by ExpandRecurringBillingEventsAction")
-                .setRequestedByRegistrar(false)
-                .setType(DOMAIN_AUTORENEW)
-                // Don't write a domain transaction record if the recurrence was ended prior to the
-                // billing time (i.e. a domain was deleted during the autorenew grace period).
-                .setDomainTransactionRecords(
-                    recurring.getRecurrenceEndTime().isBefore(billingTime)
-                        ? ImmutableSet.of()
-                        : ImmutableSet.of(
-                            DomainTransactionRecord.create(
-                                tld.getTldStr(),
-                                // We report this when the autorenew grace period ends
-                                billingTime,
-                                TransactionReportField.netRenewsFieldFromYears(1),
-                                1)))
-                .build();
-            historyEntriesBuilder.add(historyEntry);
+                      ImmutableSet.Builder<HistoryEntry> historyEntriesBuilder =
+                          new ImmutableSet.Builder<>();
+                      // Create synthetic OneTime events for all billing times that do not yet have
+                      // an event persisted.
+                      for (DateTime billingTime : difference(billingTimes, existingBillingTimes)) {
+                        // Construct a new HistoryEntry that parents over the OneTime
+                        HistoryEntry historyEntry =
+                            new HistoryEntry.Builder()
+                                .setBySuperuser(false)
+                                .setClientId(recurring.getClientId())
+                                .setModificationTime(tm().getTransactionTime())
+                                .setParent(domainKey)
+                                .setPeriod(Period.create(1, YEARS))
+                                .setReason(
+                                    "Domain autorenewal by ExpandRecurringBillingEventsAction")
+                                .setRequestedByRegistrar(false)
+                                .setType(DOMAIN_AUTORENEW)
+                                // Don't write a domain transaction record if the recurrence was
+                                // ended prior to the billing time (i.e. a domain was deleted
+                                // during the autorenew grace period).
+                                .setDomainTransactionRecords(
+                                    recurring.getRecurrenceEndTime().isBefore(billingTime)
+                                        ? ImmutableSet.of()
+                                        : ImmutableSet.of(
+                                            DomainTransactionRecord.create(
+                                                tld.getTldStr(),
+                                                // We report this when the autorenew grace period
+                                                // ends
+                                                billingTime,
+                                                TransactionReportField.netRenewsFieldFromYears(1),
+                                                1)))
+                                .build();
+                        historyEntriesBuilder.add(historyEntry);
 
-            DateTime eventTime = billingTime.minus(tld.getAutoRenewGracePeriodLength());
-            // Determine the cost for a one-year renewal.
-            Money renewCost = getDomainRenewCost(recurring.getTargetId(), eventTime, 1);
-            syntheticOneTimesBuilder.add(new OneTime.Builder()
-                .setBillingTime(billingTime)
-                .setClientId(recurring.getClientId())
-                .setCost(renewCost)
-                .setEventTime(eventTime)
-                .setFlags(union(recurring.getFlags(), Flag.SYNTHETIC))
-                .setParent(historyEntry)
-                .setPeriodYears(1)
-                .setReason(recurring.getReason())
-                .setSyntheticCreationTime(executeTime)
-                .setCancellationMatchingBillingEvent(Key.create(recurring))
-                .setTargetId(recurring.getTargetId())
-                .build());
-          }
-          Set<HistoryEntry> historyEntries = historyEntriesBuilder.build();
-          Set<OneTime> syntheticOneTimes = syntheticOneTimesBuilder.build();
-          if (!isDryRun) {
-            ImmutableSet<ImmutableObject> entitiesToSave =
-                new ImmutableSet.Builder<ImmutableObject>()
-                    .addAll(historyEntries)
-                    .addAll(syntheticOneTimes)
-                    .build();
-            ofy().save().entities(entitiesToSave).now();
-          }
-          return syntheticOneTimes.size();
-        });
+                        DateTime eventTime = billingTime.minus(tld.getAutoRenewGracePeriodLength());
+                        // Determine the cost for a one-year renewal.
+                        Money renewCost = getDomainRenewCost(recurring.getTargetId(), eventTime, 1);
+                        syntheticOneTimesBuilder.add(
+                            new OneTime.Builder()
+                                .setBillingTime(billingTime)
+                                .setClientId(recurring.getClientId())
+                                .setCost(renewCost)
+                                .setEventTime(eventTime)
+                                .setFlags(union(recurring.getFlags(), Flag.SYNTHETIC))
+                                .setParent(historyEntry)
+                                .setPeriodYears(1)
+                                .setReason(recurring.getReason())
+                                .setSyntheticCreationTime(executeTime)
+                                .setCancellationMatchingBillingEvent(recurring.createVKey())
+                                .setTargetId(recurring.getTargetId())
+                                .build());
+                      }
+                      Set<HistoryEntry> historyEntries = historyEntriesBuilder.build();
+                      Set<OneTime> syntheticOneTimes = syntheticOneTimesBuilder.build();
+                      if (!isDryRun) {
+                        ImmutableSet<ImmutableObject> entitiesToSave =
+                            new ImmutableSet.Builder<ImmutableObject>()
+                                .addAll(historyEntries)
+                                .addAll(syntheticOneTimes)
+                                .build();
+                        ofy().save().entities(entitiesToSave).now();
+                      }
+                      return syntheticOneTimes.size();
+                    });
       } catch (Throwable t) {
         getContext().incrementCounter("error: " + t.getClass().getSimpleName());
         getContext().incrementCounter(ERROR_COUNTER);
@@ -279,7 +290,8 @@ public class ExpandRecurringBillingEventsAction implements Runnable {
       return Streams.stream(oneTimesForDomain)
           .filter(
               billingEvent ->
-                  Key.create(recurringEvent)
+                  recurringEvent
+                      .createVKey()
                       .equals(billingEvent.getCancellationMatchingBillingEvent()))
           .map(OneTime::getBillingTime)
           .collect(toImmutableSet());

core/src/main/java/google/registry/bigquery/BigqueryConnection.java

@@ -442,10 +442,8 @@ public class BigqueryConnection implements AutoCloseable {
    * Returns the result of calling queryToLocalTable, but synchronously to avoid spawning new
    * background threads, which App Engine doesn't support.
    *
-   * @see <a href="https://cloud.google.com/appengine/docs/standard/java/runtime#Threads">
-   *   App Engine Runtime</a>
-   *
-   * <p>Returns the results of the query in an ImmutableTable on success.
+   * @see <a href="https://cloud.google.com/appengine/docs/standard/java/runtime#Threads">App Engine
+   *     Runtime</a>
    */
   public ImmutableTable<Integer, TableFieldSchema, Object> queryToLocalTableSync(String querySql) {
     Job job = new Job()
@@ -576,8 +574,6 @@ public class BigqueryConnection implements AutoCloseable {
 
   /**
    * Launch a job, wait for it to complete, but <i>do not</i> check for errors.
-   *
-   * @throws BigqueryJobFailureException
    */
   public Job runJob(Job job, @Nullable AbstractInputStreamContent data) {
     return checkJob(waitForJob(launchJob(job, data)));

core/src/main/java/google/registry/config/RegistryConfig.java

@@ -1512,11 +1512,21 @@ public final class RegistryConfig {
     return CONFIG_SETTINGS.get().hibernate.hikariConnectionTimeout;
   }
 
+  /** Returns the minimum idle connections for HikariCP. */
+  public static String getHibernateHikariMinimumIdle() {
+    return CONFIG_SETTINGS.get().hibernate.hikariMinimumIdle;
+  }
+
   /** Returns the maximum pool size for HikariCP. */
   public static String getHibernateHikariMaximumPoolSize() {
     return CONFIG_SETTINGS.get().hibernate.hikariMaximumPoolSize;
   }
 
+  /** Returns the idle timeout for HikariCP. */
+  public static String getHibernateHikariIdleTimeout() {
+    return CONFIG_SETTINGS.get().hibernate.hikariIdleTimeout;
+  }
+
   /** Returns the roid suffix to be used for the roids of all contacts and hosts. */
   public static String getContactAndHostRoidSuffix() {
     return CONFIG_SETTINGS.get().registryPolicy.contactAndHostRoidSuffix;

core/src/main/java/google/registry/config/RegistryConfigSettings.java

@@ -112,7 +112,9 @@ public class RegistryConfigSettings {
     public String connectionIsolation;
     public String logSqlQueries;
     public String hikariConnectionTimeout;
+    public String hikariMinimumIdle;
     public String hikariMaximumPoolSize;
+    public String hikariIdleTimeout;
   }
 
   /** Configuration for Cloud SQL. */

core/src/main/java/google/registry/config/files/default-config.yaml

@@ -207,17 +207,21 @@ hibernate:
 
   # Connection pool configurations.
   hikariConnectionTimeout: 20000
-
   # We occasionally received "Connection is not available, request timed out"
   # exception when setting minimumIdle to 0 and it turned out it is a bug (See
-  # https://github.com/brettwooldridge/HikariCP/issues/1212) in HikariCP and
-  # the workaround is to use a fixed size connection pool.
+  # https://github.com/brettwooldridge/HikariCP/issues/1212) in HikariCP.
+  #
+  # We tried to use a fixed size pool but ran into an issue(See b/155383029),
+  # so we need further investigation to figure out the proper size of the pool.
   #
   # HikariCP also recommends not setting minimumIdle for maximum performance
   # and responsiveness to spike demands (See
   # https://github.com/brettwooldridge/HikariCP).
-  # TODO(b/154720215): Experiment with a smaller pool size.
-  hikariMaximumPoolSize: 20
+  #
+  # TODO(b/154720215): Investigate the long term fix.
+  hikariMinimumIdle: 1
+  hikariMaximumPoolSize: 10
+  hikariIdleTimeout: 300000
 
 cloudSql:
   # jdbc url for the Cloud SQL database.

core/src/main/java/google/registry/dns/writer/dnsupdate/DnsMessageTransport.java

@@ -84,7 +84,7 @@ public class DnsMessageTransport {
    * @param query a message to send
    * @return the response received from the server
    * @throws IOException if the Socket input/output streams throws one
-   * @throws IllegalArgumentException if the query is too large to be sent (> 65535 bytes)
+   * @throws IllegalArgumentException if the query is too large to be sent (> 65535 bytes)
    */
   public Message send(Message query) throws IOException {
     try (Socket socket = factory.createSocket(InetAddress.getByName(updateHost), DNS_PORT)) {

core/src/main/java/google/registry/export/BigqueryPollJobAction.java

@@ -73,8 +73,10 @@ public class BigqueryPollJobAction implements Runnable {
 
   @Override
   public void run() {
-    checkJobOutcome();  // Throws a NotModifiedException if the job hasn't completed.
-    if (payload == null || payload.length == 0) {
+    boolean jobOutcome =
+        checkJobOutcome(); // Throws a NotModifiedException if the job hasn't completed.
+    // If the job failed, do not enqueue the next step.
+    if (!jobOutcome || payload == null || payload.length == 0) {
       return;
     }
     // If there is a payload, it's a chained task, so enqueue it.

core/src/main/java/google/registry/flows/EppXmlSanitizer.java

@@ -42,8 +42,8 @@ import javax.xml.stream.events.XMLEvent;
 /**
  * Sanitizes sensitive data in incoming/outgoing EPP XML messages.
  *
- * <p>Current implementation masks user credentials (text following <pw> and <newPW> tags) as
- * follows:
+ * <p>Current implementation masks user credentials (text following &lt;pw&gt; and &lt;newPW&gt;
+ * tags) as follows:
  *
  * <ul>
  *   <li>A control character (in ranges [0 - 1F] and [7F - 9F]) is replaced with 'C'.

core/src/main/java/google/registry/flows/ResourceFlowUtils.java

@@ -48,6 +48,7 @@ import google.registry.model.eppcommon.AuthInfo;
 import google.registry.model.eppcommon.StatusValue;
 import google.registry.model.index.ForeignKeyIndex;
 import google.registry.model.transfer.TransferStatus;
+import google.registry.persistence.VKey;
 import java.util.List;
 import java.util.Objects;
 import java.util.Optional;
@@ -96,8 +97,9 @@ public final class ResourceFlowUtils {
                       queryForLinkedDomains(fki.getResourceKey(), now)
                           .limit(FAILFAST_CHECK_COUNT)
                           .keys();
+                  VKey<R> resourceVKey = VKey.createOfy(resourceClass, fki.getResourceKey());
                   Predicate<DomainBase> predicate =
-                      domain -> getPotentialReferences.apply(domain).contains(fki.getResourceKey());
+                      domain -> getPotentialReferences.apply(domain).contains(resourceVKey);
                   return ofy().load().keys(keys).values().stream().anyMatch(predicate)
                       ? new ResourceToDeleteIsReferencedException()
                       : null;
@@ -184,9 +186,8 @@ public final class ResourceFlowUtils {
     }
     // The roid should match one of the contacts.
     Optional<Key<ContactResource>> foundContact =
-        domain
-            .getReferencedContacts()
-            .stream()
+        domain.getReferencedContacts().stream()
+            .map(VKey::getOfyKey)
             .filter(key -> key.getName().equals(authRepoId))
             .findFirst();
     if (!foundContact.isPresent()) {

core/src/main/java/google/registry/flows/custom/DomainCheckFlowCustomLogic.java

@@ -75,7 +75,7 @@ public class DomainCheckFlowCustomLogic extends BaseFlowCustomLogic {
 
     /**
      * The time to perform the domain check as of. This defaults to the current time, but can be
-     * overridden in v>=0.12 of the fee extension.
+     * overridden in v>=0.12 of the fee extension.
      */
     public abstract DateTime asOfDate();
 
@@ -105,7 +105,7 @@ public class DomainCheckFlowCustomLogic extends BaseFlowCustomLogic {
 
     /**
      * The time to perform the domain check as of. This defaults to the current time, but can be
-     * overridden in v>=0.12 of the fee extension.
+     * overridden in v>=0.12 of the fee extension.
      */
     public abstract DateTime asOfDate();
 

core/src/main/java/google/registry/flows/domain/DomainCreateFlow.java

@@ -77,6 +77,7 @@ import google.registry.model.billing.BillingEvent;
 import google.registry.model.billing.BillingEvent.Flag;
 import google.registry.model.billing.BillingEvent.Reason;
 import google.registry.model.billing.BillingEvent.Recurring;
+import google.registry.model.contact.ContactResource;
 import google.registry.model.domain.DomainBase;
 import google.registry.model.domain.DomainCommand;
 import google.registry.model.domain.DomainCommand.Create;
@@ -352,7 +353,7 @@ public class DomainCreateFlow implements TransactionalFlow {
             .setLaunchNotice(hasClaimsNotice ? launchCreate.get().getNotice() : null)
             .setSmdId(signedMarkId)
             .setDsData(secDnsCreate.isPresent() ? secDnsCreate.get().getDsData() : null)
-            .setRegistrant(command.getRegistrant())
+            .setRegistrant(VKey.createOfy(ContactResource.class, command.getRegistrant()))
             .setAuthInfo(command.getAuthInfo())
             .setFullyQualifiedDomainName(targetId)
             .setNameservers(
@@ -533,7 +534,7 @@ public class DomainCreateFlow implements TransactionalFlow {
         .setPeriodYears(years)
         .setCost(feesAndCredits.getCreateCost())
         .setEventTime(now)
-        .setAllocationToken(allocationToken.map(Key::create).orElse(null))
+        .setAllocationToken(allocationToken.map(AllocationToken::createVKey).orElse(null))
         .setBillingTime(
             now.plus(
                 isAnchorTenant

core/src/main/java/google/registry/flows/domain/DomainDeleteFlow.java

@@ -212,6 +212,28 @@ public final class DomainDeleteFlow implements TransactionalFlow {
       builder.setDeletePollMessage(Key.create(deletePollMessage));
     }
 
+    // Cancel any grace periods that were still active, and set the expiration time accordingly.
+    DateTime newExpirationTime = existingDomain.getRegistrationExpirationTime();
+    for (GracePeriod gracePeriod : existingDomain.getGracePeriods()) {
+      // No cancellation is written if the grace period was not for a billable event.
+      if (gracePeriod.hasBillingEvent()) {
+        entitiesToSave.add(
+            BillingEvent.Cancellation.forGracePeriod(gracePeriod, historyEntry, targetId));
+        if (gracePeriod.getOneTimeBillingEvent() != null) {
+          // Take the amount of amount of registration time being refunded off the expiration time.
+          // This can be either add grace periods or renew grace periods.
+          BillingEvent.OneTime oneTime =
+              ofy().load().key(gracePeriod.getOneTimeBillingEvent()).now();
+          newExpirationTime = newExpirationTime.minusYears(oneTime.getPeriodYears());
+        } else if (gracePeriod.getRecurringBillingEvent() != null) {
+          // Take 1 year off the registration if in the autorenew grace period (no need to load the
+          // recurring billing event; all autorenews are for 1 year).
+          newExpirationTime = newExpirationTime.minusYears(1);
+        }
+      }
+    }
+    builder.setRegistrationExpirationTime(newExpirationTime);
+
     DomainBase newDomain = builder.build();
     updateForeignKeyIndexDeletionTime(newDomain);
     handlePendingTransferOnDelete(existingDomain, newDomain, now, historyEntry);
@@ -221,14 +243,7 @@ public final class DomainDeleteFlow implements TransactionalFlow {
     // event and poll message will already have been deleted in
     // ResourceDeleteFlow since it's listed in serverApproveEntities.
     dnsQueue.addDomainRefreshTask(existingDomain.getFullyQualifiedDomainName());
-    // Cancel any grace periods that were still active.
-    for (GracePeriod gracePeriod : existingDomain.getGracePeriods()) {
-      // No cancellation is written if the grace period was not for a billable event.
-      if (gracePeriod.hasBillingEvent()) {
-        entitiesToSave.add(
-            BillingEvent.Cancellation.forGracePeriod(gracePeriod, historyEntry, targetId));
-      }
-    }
+
     entitiesToSave.add(newDomain, historyEntry);
     EntityChanges entityChanges = flowCustomLogic.beforeSave(
         BeforeSaveParameters.newBuilder()

core/src/main/java/google/registry/flows/domain/DomainFlowUtils.java

@@ -35,6 +35,7 @@ import static google.registry.model.registry.Registry.TldState.START_DATE_SUNRIS
 import static google.registry.model.registry.label.ReservationType.FULLY_BLOCKED;
 import static google.registry.model.registry.label.ReservationType.RESERVED_FOR_ANCHOR_TENANT;
 import static google.registry.model.registry.label.ReservationType.RESERVED_FOR_SPECIFIC_USE;
+import static google.registry.persistence.transaction.TransactionManagerFactory.tm;
 import static google.registry.pricing.PricingEngineProxy.isDomainPremium;
 import static google.registry.util.CollectionUtils.nullToEmpty;
 import static google.registry.util.DateTimeUtils.END_OF_TIME;
@@ -120,6 +121,7 @@ import google.registry.model.reporting.DomainTransactionRecord;
 import google.registry.model.reporting.DomainTransactionRecord.TransactionReportField;
 import google.registry.model.reporting.HistoryEntry;
 import google.registry.model.tmch.ClaimsListShard;
+import google.registry.persistence.VKey;
 import google.registry.tldconfig.idn.IdnLabelValidator;
 import google.registry.util.Idn;
 import java.math.BigDecimal;
@@ -309,7 +311,10 @@ public class DomainFlowUtils {
       Set<Key<HostResource>> nameservers)
       throws EppException {
     ImmutableList.Builder<Key<? extends EppResource>> keysToLoad = new ImmutableList.Builder<>();
-    contacts.stream().map(DesignatedContact::getContactKey).forEach(keysToLoad::add);
+    contacts.stream()
+        .map(DesignatedContact::getContactKey)
+        .map(VKey::getOfyKey)
+        .forEach(keysToLoad::add);
     Optional.ofNullable(registrant).ifPresent(keysToLoad::add);
     keysToLoad.addAll(nameservers);
     verifyNotInPendingDelete(EppResource.loadCached(keysToLoad.build()).values());
@@ -355,7 +360,7 @@ public class DomainFlowUtils {
         contacts.stream()
             .collect(
                 toImmutableSetMultimap(
-                    DesignatedContact::getType, DesignatedContact::getContactKey));
+                    DesignatedContact::getType, contact -> contact.getContactKey().getOfyKey()));
 
     // If any contact type has multiple contacts:
     if (contactsByType.asMap().values().stream().anyMatch(v -> v.size() > 1)) {
@@ -978,7 +983,7 @@ public class DomainFlowUtils {
     for (DesignatedContact contact : contacts) {
       builder.add(
           ForeignKeyedDesignatedContact.create(
-              contact.getType(), ofy().load().key(contact.getContactKey()).now().getContactId()));
+              contact.getType(), tm().load(contact.getContactKey()).getContactId()));
     }
     return builder.build();
   }

core/src/main/java/google/registry/flows/domain/DomainInfoFlow.java

@@ -21,7 +21,6 @@ import static google.registry.flows.domain.DomainFlowUtils.addSecDnsExtensionIfP
 import static google.registry.flows.domain.DomainFlowUtils.handleFeeRequest;
 import static google.registry.flows.domain.DomainFlowUtils.loadForeignKeyedDesignatedContacts;
 import static google.registry.model.EppResourceUtils.loadByForeignKey;
-import static google.registry.model.ofy.ObjectifyService.ofy;
 import static google.registry.persistence.transaction.TransactionManagerFactory.tm;
 
 import com.google.common.collect.ImmutableList;
@@ -102,16 +101,16 @@ public final class DomainInfoFlow implements Flow {
     flowCustomLogic.afterValidation(
         AfterValidationParameters.newBuilder().setDomain(domain).build());
     // Prefetch all referenced resources. Calling values() blocks until loading is done.
-    // We do nameservers separately since they've been converted to VKey.
     tm().load(domain.getNameservers());
-    ofy().load().values(domain.getReferencedContacts()).values();
+    tm().load(domain.getReferencedContacts());
     // Registrars can only see a few fields on unauthorized domains.
     // This is a policy decision that is left up to us by the rfcs.
-    DomainInfoData.Builder infoBuilder = DomainInfoData.newBuilder()
-        .setFullyQualifiedDomainName(domain.getFullyQualifiedDomainName())
-        .setRepoId(domain.getRepoId())
-        .setCurrentSponsorClientId(domain.getCurrentSponsorClientId())
-        .setRegistrant(ofy().load().key(domain.getRegistrant()).now().getContactId());
+    DomainInfoData.Builder infoBuilder =
+        DomainInfoData.newBuilder()
+            .setFullyQualifiedDomainName(domain.getFullyQualifiedDomainName())
+            .setRepoId(domain.getRepoId())
+            .setCurrentSponsorClientId(domain.getCurrentSponsorClientId())
+            .setRegistrant(tm().load(domain.getRegistrant()).getContactId());
     // If authInfo is non-null, then the caller is authorized to see the full information since we
     // will have already verified the authInfo is valid.
     if (clientId.equals(domain.getCurrentSponsorClientId()) || authInfo.isPresent()) {

core/src/main/java/google/registry/flows/domain/DomainUpdateFlow.java

@@ -60,6 +60,7 @@ import google.registry.flows.domain.DomainFlowUtils.MissingRegistrantException;
 import google.registry.model.ImmutableObject;
 import google.registry.model.billing.BillingEvent;
 import google.registry.model.billing.BillingEvent.Reason;
+import google.registry.model.contact.ContactResource;
 import google.registry.model.domain.DomainBase;
 import google.registry.model.domain.DomainCommand.Update;
 import google.registry.model.domain.DomainCommand.Update.AddRemove;
@@ -256,7 +257,12 @@ public final class DomainUpdateFlow implements TransactionalFlow {
                     .collect(toImmutableSet()))
             .addContacts(add.getContacts())
             .removeContacts(remove.getContacts())
-            .setRegistrant(firstNonNull(change.getRegistrant(), domain.getRegistrant()))
+            .setRegistrant(
+                firstNonNull(
+                    change.getRegistrant() != null
+                        ? VKey.createOfy(ContactResource.class, change.getRegistrant())
+                        : null,
+                    domain.getRegistrant()))
             .setAuthInfo(firstNonNull(change.getAuthInfo(), domain.getAuthInfo()));
     return domainBuilder.build();
   }
@@ -269,7 +275,7 @@ public final class DomainUpdateFlow implements TransactionalFlow {
 
   private void validateNewState(DomainBase newDomain) throws EppException {
     validateNoDuplicateContacts(newDomain.getContacts());
-    validateRequiredContactsPresent(newDomain.getRegistrant(), newDomain.getContacts());
+    validateRequiredContactsPresent(newDomain.getRegistrant().getOfyKey(), newDomain.getContacts());
     validateDsData(newDomain.getDsData());
     validateNameserversCountForTld(
         newDomain.getTld(),

core/src/main/java/google/registry/flows/host/HostDeleteFlow.java

@@ -14,7 +14,6 @@
 
 package google.registry.flows.host;
 
-import static com.google.common.collect.ImmutableSet.toImmutableSet;
 import static google.registry.flows.FlowUtils.validateClientIsLoggedIn;
 import static google.registry.flows.ResourceFlowUtils.failfastForAsyncDelete;
 import static google.registry.flows.ResourceFlowUtils.loadAndVerifyExistence;
@@ -82,17 +81,6 @@ public final class HostDeleteFlow implements TransactionalFlow {
   @Inject EppResponse.Builder responseBuilder;
   @Inject HostDeleteFlow() {}
 
-  /**
-   * Hack to convert DomainBase's nameserver VKey's to Ofy Key's.
-   *
-   * <p>We currently need this because {@code failfastForAsyncDelete()} checks to see if a name is
-   * in the ofy keys and is used for both nameservers and contacts. When we convert contacts to
-   * VKey's, we can remove this and do the conversion in {@code failfastForAsyncDelete()}.
-   */
-  private static ImmutableSet<Key<HostResource>> getNameserverOfyKeys(DomainBase domain) {
-    return domain.getNameservers().stream().map(key -> key.getOfyKey()).collect(toImmutableSet());
-  }
-
   @Override
   public final EppResponse run() throws EppException {
     extensionManager.register(MetadataExtension.class);
@@ -100,7 +88,7 @@ public final class HostDeleteFlow implements TransactionalFlow {
     validateClientIsLoggedIn(clientId);
     DateTime now = tm().getTransactionTime();
     validateHostName(targetId);
-    failfastForAsyncDelete(targetId, now, HostResource.class, HostDeleteFlow::getNameserverOfyKeys);
+    failfastForAsyncDelete(targetId, now, HostResource.class, DomainBase::getNameservers);
     HostResource existingHost = loadAndVerifyExistence(HostResource.class, targetId, now);
     verifyNoDisallowedStatuses(existingHost, DISALLOWED_STATUSES);
     if (!isSuperuser) {

core/src/main/java/google/registry/model/EppResource.java

@@ -135,7 +135,7 @@ public abstract class EppResource extends BackupGroupRoot implements Buildable {
   @Transient
   ImmutableSortedMap<DateTime, Key<CommitLogManifest>> revisions = ImmutableSortedMap.of();
 
-  public final String getRepoId() {
+  public String getRepoId() {
     return repoId;
   }
 

core/src/main/java/google/registry/model/ModelUtils.java

@@ -34,6 +34,7 @@ import com.googlecode.objectify.Key;
 import com.googlecode.objectify.annotation.Id;
 import com.googlecode.objectify.annotation.Ignore;
 import com.googlecode.objectify.annotation.Parent;
+import google.registry.persistence.VKey;
 import java.lang.reflect.Array;
 import java.lang.reflect.Field;
 import java.lang.reflect.Modifier;
@@ -139,10 +140,13 @@ public class ModelUtils {
 
       // If the field's type is the same as the field's class object, then it's a non-parameterized
       // type, and thus we just add it directly. We also don't bother looking at the parameterized
-      // types of Key objects, since they are just references to other objects and don't actually
-      // embed themselves in the persisted object anyway.
+      // types of Key and VKey objects, since they are just references to other objects and don't
+      // actually embed themselves in the persisted object anyway.
       Class<?> fieldClazz = field.getType();
       Type fieldType = field.getGenericType();
+      if (VKey.class.equals(fieldClazz)) {
+        continue;
+      }
       builder.add(fieldClazz);
       if (fieldType.equals(fieldClazz) || Key.class.equals(clazz)) {
         continue;

core/src/main/java/google/registry/model/OteStats.java

@@ -50,7 +50,8 @@ import java.util.stream.Collectors;
 public class OteStats {
 
   /**
-   * Returns the statistics about the OT&E actions that have been taken by a particular registrar.
+   * Returns the statistics about the OT&E actions that have been taken by a particular
+   * registrar.
    */
   public static OteStats getFromRegistrar(String registrarName) {
     return new OteStats().recordRegistrarHistory(registrarName);

core/src/main/java/google/registry/model/UpdateAutoTimestamp.java

@@ -30,7 +30,7 @@ public class UpdateAutoTimestamp extends ImmutableObject {
 
   DateTime timestamp;
 
-  /** Returns the timestamp, or {@link START_OF_TIME} if it's null. */
+  /** Returns the timestamp, or {@code START_OF_TIME} if it's null. */
   public DateTime getTimestamp() {
     return Optional.ofNullable(timestamp).orElse(START_OF_TIME);
   }

core/src/main/java/google/registry/model/billing/BillingEvent.java

@@ -30,6 +30,7 @@ import com.google.common.collect.Sets;
 import com.googlecode.objectify.Key;
 import com.googlecode.objectify.annotation.Entity;
 import com.googlecode.objectify.annotation.Id;
+import com.googlecode.objectify.annotation.Ignore;
 import com.googlecode.objectify.annotation.IgnoreSave;
 import com.googlecode.objectify.annotation.Index;
 import com.googlecode.objectify.annotation.Parent;
@@ -43,14 +44,28 @@ import google.registry.model.domain.rgp.GracePeriodStatus;
 import google.registry.model.domain.token.AllocationToken;
 import google.registry.model.reporting.HistoryEntry;
 import google.registry.model.transfer.TransferData.TransferServerApproveEntity;
+import google.registry.persistence.VKey;
+import google.registry.persistence.WithLongVKey;
 import java.util.Objects;
 import java.util.Optional;
 import java.util.Set;
 import javax.annotation.Nullable;
+import javax.persistence.AttributeOverride;
+import javax.persistence.AttributeOverrides;
+import javax.persistence.Column;
+import javax.persistence.Embedded;
+import javax.persistence.EnumType;
+import javax.persistence.Enumerated;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.MappedSuperclass;
+import javax.persistence.Transient;
 import org.joda.money.Money;
 import org.joda.time.DateTime;
 
 /** A billable event in a domain's lifecycle. */
+@MappedSuperclass
+@WithLongVKey
 public abstract class BillingEvent extends ImmutableObject
     implements Buildable, TransferServerApproveEntity {
 
@@ -93,24 +108,41 @@ public abstract class BillingEvent extends ImmutableObject
 
   /** Entity id. */
   @Id
-  long id;
+  @javax.persistence.Id
+  @GeneratedValue(strategy = GenerationType.IDENTITY)
+  Long id;
 
-  @Parent
-  @DoNotHydrate
-  Key<HistoryEntry> parent;
+  @Parent @DoNotHydrate @Transient Key<HistoryEntry> parent;
 
   /** The registrar to bill. */
   @Index
+  @Column(nullable = false)
   String clientId;
 
+  /** Revision id of the entry in DomainHistory table that ths bill belongs to. */
+  // TODO(shicong): Add foreign key constraint when DomainHistory table is generated
+  @Ignore
+  @Column(nullable = false)
+  Long domainHistoryRevisionId;
+
+  /** ID of the EPP resource that the bill is for. */
+  // TODO(shicong): Add foreign key constraint when we expand DatastoreHelp for Postgresql
+  @Ignore
+  @Column(nullable = false)
+  String domainRepoId;
+
   /** When this event was created. For recurring events, this is also the recurrence start time. */
   @Index
+  @Column(nullable = false)
   DateTime eventTime;
 
   /** The reason for the bill. */
+  @Enumerated(EnumType.STRING)
+  @Column(nullable = false)
   Reason reason;
 
   /** The fully qualified domain name of the domain that the bill is for. */
+  @Column(name = "domain_name", nullable = false)
   String targetId;
 
   @Nullable
@@ -120,6 +152,14 @@ public abstract class BillingEvent extends ImmutableObject
     return clientId;
   }
 
+  public long getDomainHistoryRevisionId() {
+    return domainHistoryRevisionId;
+  }
+
+  public String getDomainRepoId() {
+    return domainRepoId;
+  }
+
   public DateTime getEventTime() {
     return eventTime;
   }
@@ -163,7 +203,7 @@ public abstract class BillingEvent extends ImmutableObject
       return thisCastToDerived();
     }
 
-    public B setId(Long id) {
+    public B setId(long id) {
       getInstance().id = id;
       return thisCastToDerived();
     }
@@ -173,6 +213,16 @@ public abstract class BillingEvent extends ImmutableObject
       return thisCastToDerived();
     }
 
+    public B setDomainHistoryRevisionId(long domainHistoryRevisionId) {
+      getInstance().domainHistoryRevisionId = domainHistoryRevisionId;
+      return thisCastToDerived();
+    }
+
+    public B setDomainRepoId(String domainRepoId) {
+      getInstance().domainRepoId = domainRepoId;
+      return thisCastToDerived();
+    }
+
     public B setEventTime(DateTime eventTime) {
       getInstance().eventTime = eventTime;
       return thisCastToDerived();
@@ -194,6 +244,7 @@ public abstract class BillingEvent extends ImmutableObject
     }
 
     public B setParent(Key<HistoryEntry> parentKey) {
+      // TODO(shicong): Figure out how to set domainHistoryRevisionId and domainRepoId
       getInstance().parent = parentKey;
       return thisCastToDerived();
     }
@@ -213,9 +264,23 @@ public abstract class BillingEvent extends ImmutableObject
   /** A one-time billable event. */
   @ReportedOn
   @Entity
+  @javax.persistence.Entity(name = "BillingEvent")
+  @javax.persistence.Table(
+      indexes = {
+        @javax.persistence.Index(columnList = "clientId"),
+        @javax.persistence.Index(columnList = "eventTime"),
+        @javax.persistence.Index(columnList = "billingTime"),
+        @javax.persistence.Index(columnList = "syntheticCreationTime"),
+        @javax.persistence.Index(columnList = "allocation_token_id")
+      })
+  @AttributeOverride(name = "id", column = @Column(name = "billing_event_id"))
   public static class OneTime extends BillingEvent {
 
     /** The billable value. */
+    @AttributeOverrides({
+      @AttributeOverride(name = "money.amount", column = @Column(name = "cost_amount")),
+      @AttributeOverride(name = "money.currency", column = @Column(name = "cost_currency"))
+    })
     Money cost;
 
     /** When the cost should be billed. */
@@ -223,8 +288,8 @@ public abstract class BillingEvent extends ImmutableObject
     DateTime billingTime;
 
     /**
-     * The period in years of the action being billed for, if applicable, otherwise null.
-     * Used for financial reporting.
+     * The period in years of the action being billed for, if applicable, otherwise null. Used for
+     * financial reporting.
      */
     @IgnoreSave(IfNull.class)
     Integer periodYears = null;
@@ -240,15 +305,21 @@ public abstract class BillingEvent extends ImmutableObject
 
     /**
      * For {@link Flag#SYNTHETIC} events, a {@link Key} to the {@link BillingEvent} from which this
-     * OneTime was created. This is needed in order to properly match billing events against
-     * {@link Cancellation}s.
+     * OneTime was created. This is needed in order to properly match billing events against {@link
+     * Cancellation}s.
      */
-    Key<? extends BillingEvent> cancellationMatchingBillingEvent;
+    @Column(name = "cancellation_matching_billing_recurrence_id")
+    VKey<? extends BillingEvent> cancellationMatchingBillingEvent;
 
     /**
      * The {@link AllocationToken} used in the creation of this event, or null if one was not used.
+     *
+     * <p>TODO(shicong): Add foreign key constraint when AllocationToken schema is generated
      */
-    @Index @Nullable Key<AllocationToken> allocationToken;
+    @Column(name = "allocation_token_id")
+    @Index
+    @Nullable
+    VKey<AllocationToken> allocationToken;
 
     public Money getCost() {
       return cost;
@@ -266,14 +337,18 @@ public abstract class BillingEvent extends ImmutableObject
       return syntheticCreationTime;
     }
 
-    public Key<? extends BillingEvent> getCancellationMatchingBillingEvent() {
+    public VKey<? extends BillingEvent> getCancellationMatchingBillingEvent() {
       return cancellationMatchingBillingEvent;
     }
 
-    public Optional<Key<AllocationToken>> getAllocationToken() {
+    public Optional<VKey<AllocationToken>> getAllocationToken() {
       return Optional.ofNullable(allocationToken);
     }
 
+    public VKey<OneTime> createVKey() {
+      return VKey.createOfy(getClass(), Key.create(this));
+    }
+
     @Override
     public Builder asBuilder() {
       return new Builder(clone(this));
@@ -311,12 +386,12 @@ public abstract class BillingEvent extends ImmutableObject
       }
 
       public Builder setCancellationMatchingBillingEvent(
-          Key<? extends BillingEvent> cancellationMatchingBillingEvent) {
+          VKey<? extends BillingEvent> cancellationMatchingBillingEvent) {
         getInstance().cancellationMatchingBillingEvent = cancellationMatchingBillingEvent;
         return this;
       }
 
-      public Builder setAllocationToken(@Nullable Key<AllocationToken> allocationToken) {
+      public Builder setAllocationToken(@Nullable VKey<AllocationToken> allocationToken) {
         getInstance().allocationToken = allocationToken;
         return this;
       }
@@ -361,6 +436,15 @@ public abstract class BillingEvent extends ImmutableObject
    */
   @ReportedOn
   @Entity
+  @javax.persistence.Entity(name = "BillingRecurrence")
+  @javax.persistence.Table(
+      indexes = {
+        @javax.persistence.Index(columnList = "clientId"),
+        @javax.persistence.Index(columnList = "eventTime"),
+        @javax.persistence.Index(columnList = "recurrenceEndTime"),
+        @javax.persistence.Index(columnList = "recurrence_time_of_year")
+      })
+  @AttributeOverride(name = "id", column = @Column(name = "billing_recurrence_id"))
   public static class Recurring extends BillingEvent {
 
     /**
@@ -384,6 +468,10 @@ public abstract class BillingEvent extends ImmutableObject
      * model, whereas the billing time is a fixed {@link org.joda.time.Duration} later.
      */
     @Index
+    @Embedded
+    @AttributeOverrides({
+      @AttributeOverride(name = "timeString", column = @Column(name = "recurrence_time_of_year"))
+    })
     TimeOfYear recurrenceTimeOfYear;
 
     public DateTime getRecurrenceEndTime() {
@@ -394,6 +482,10 @@ public abstract class BillingEvent extends ImmutableObject
       return recurrenceTimeOfYear;
     }
 
+    public VKey<Recurring> createVKey() {
+      return VKey.createOfy(getClass(), Key.create(this));
+    }
+
     @Override
     public Builder asBuilder() {
       return new Builder(clone(this));
@@ -434,6 +526,14 @@ public abstract class BillingEvent extends ImmutableObject
    */
   @ReportedOn
   @Entity
+  @javax.persistence.Entity(name = "BillingCancellation")
+  @javax.persistence.Table(
+      indexes = {
+        @javax.persistence.Index(columnList = "clientId"),
+        @javax.persistence.Index(columnList = "eventTime"),
+        @javax.persistence.Index(columnList = "billingTime")
+      })
+  @AttributeOverride(name = "id", column = @Column(name = "billing_cancellation_id"))
   public static class Cancellation extends BillingEvent {
 
     /** The billing time of the charge that is being cancelled. */
@@ -446,7 +546,8 @@ public abstract class BillingEvent extends ImmutableObject
      * <p>Although the type is {@link Key} the name "ref" is preserved for historical reasons.
      */
     @IgnoreSave(IfNull.class)
-    Key<BillingEvent.OneTime> refOneTime = null;
+    @Column(name = "billing_event_id")
+    VKey<BillingEvent.OneTime> refOneTime = null;
 
     /**
      * The recurring billing event to cancel, or null for non-autorenew cancellations.
@@ -454,13 +555,14 @@ public abstract class BillingEvent extends ImmutableObject
      * <p>Although the type is {@link Key} the name "ref" is preserved for historical reasons.
      */
     @IgnoreSave(IfNull.class)
-    Key<BillingEvent.Recurring> refRecurring = null;
+    @Column(name = "billing_recurrence_id")
+    VKey<BillingEvent.Recurring> refRecurring = null;
 
     public DateTime getBillingTime() {
       return billingTime;
     }
 
-    public Key<? extends BillingEvent> getEventKey() {
+    public VKey<? extends BillingEvent> getEventKey() {
       return firstNonNull(refOneTime, refRecurring);
     }
 
@@ -492,13 +594,19 @@ public abstract class BillingEvent extends ImmutableObject
           .setParent(historyEntry);
       // Set the grace period's billing event using the appropriate Cancellation builder method.
       if (gracePeriod.getOneTimeBillingEvent() != null) {
-        builder.setOneTimeEventKey(gracePeriod.getOneTimeBillingEvent());
+        builder.setOneTimeEventKey(
+            VKey.createOfy(BillingEvent.OneTime.class, gracePeriod.getOneTimeBillingEvent()));
       } else if (gracePeriod.getRecurringBillingEvent() != null) {
-        builder.setRecurringEventKey(gracePeriod.getRecurringBillingEvent());
+        builder.setRecurringEventKey(
+            VKey.createOfy(BillingEvent.Recurring.class, gracePeriod.getRecurringBillingEvent()));
       }
       return builder.build();
     }
 
+    public VKey<Cancellation> createVKey() {
+      return VKey.createOfy(getClass(), Key.create(this));
+    }
+
     @Override
     public Builder asBuilder() {
       return new Builder(clone(this));
@@ -518,12 +626,12 @@ public abstract class BillingEvent extends ImmutableObject
         return this;
       }
 
-      public Builder setOneTimeEventKey(Key<BillingEvent.OneTime> eventKey) {
+      public Builder setOneTimeEventKey(VKey<BillingEvent.OneTime> eventKey) {
         getInstance().refOneTime = eventKey;
         return this;
       }
 
-      public Builder setRecurringEventKey(Key<BillingEvent.Recurring> eventKey) {
+      public Builder setRecurringEventKey(VKey<BillingEvent.Recurring> eventKey) {
         getInstance().refRecurring = eventKey;
         return this;
       }
@@ -540,9 +648,7 @@ public abstract class BillingEvent extends ImmutableObject
     }
   }
 
-  /**
-   * An event representing a modification of an existing one-time billing event.
-   */
+  /** An event representing a modification of an existing one-time billing event. */
   @ReportedOn
   @Entity
   public static class Modification extends BillingEvent {

core/src/main/java/google/registry/model/common/Cursor.java

@@ -21,6 +21,7 @@ import static google.registry.model.ofy.ObjectifyService.ofy;
 import static google.registry.util.DateTimeUtils.START_OF_TIME;
 
 import com.google.common.base.Splitter;
+import com.google.common.collect.ImmutableList;
 import com.googlecode.objectify.Key;
 import com.googlecode.objectify.annotation.Entity;
 import com.googlecode.objectify.annotation.Id;
@@ -28,6 +29,8 @@ import com.googlecode.objectify.annotation.Parent;
 import google.registry.model.ImmutableObject;
 import google.registry.model.UpdateAutoTimestamp;
 import google.registry.model.registry.Registry;
+import google.registry.schema.replay.DatastoreEntity;
+import google.registry.schema.replay.SqlEntity;
 import java.util.List;
 import org.joda.time.DateTime;
 
@@ -37,7 +40,7 @@ import org.joda.time.DateTime;
  * as scoped on {@link EntityGroupRoot}.
  */
 @Entity
-public class Cursor extends ImmutableObject {
+public class Cursor extends ImmutableObject implements DatastoreEntity {
 
   /** The types of cursors, used as the string id field for each cursor in Datastore. */
   public enum CursorType {
@@ -134,6 +137,11 @@ public class Cursor extends ImmutableObject {
     return CursorType.valueOf(String.join("_", id.subList(1, id.size())));
   }
 
+  @Override
+  public ImmutableList<SqlEntity> toSqlEntities() {
+    return ImmutableList.of(); // Cursors are not converted since they are ephemeral
+  }
+
   /**
    * Checks that the type of the scoped object (or null) matches the required type for the specified
    * cursor (or null, if the cursor is a global cursor).

core/src/main/java/google/registry/model/common/EntityGroupRoot.java

@@ -14,10 +14,13 @@
 
 package google.registry.model.common;
 
+import com.google.common.collect.ImmutableList;
 import com.googlecode.objectify.Key;
 import com.googlecode.objectify.annotation.Entity;
 import com.googlecode.objectify.annotation.Id;
 import google.registry.model.BackupGroupRoot;
+import google.registry.schema.replay.DatastoreEntity;
+import google.registry.schema.replay.SqlEntity;
 
 /**
  * The root key for the entity group which is known as the cross-tld entity group for historical
@@ -34,7 +37,7 @@ import google.registry.model.BackupGroupRoot;
  * the entity group for the single namespace where global data applicable for all TLDs lived.
  */
 @Entity
-public class EntityGroupRoot extends BackupGroupRoot {
+public class EntityGroupRoot extends BackupGroupRoot implements DatastoreEntity {
 
   @SuppressWarnings("unused")
   @Id
@@ -44,4 +47,9 @@ public class EntityGroupRoot extends BackupGroupRoot {
   public static Key<EntityGroupRoot> getCrossTldKey() {
     return Key.create(EntityGroupRoot.class, "cross-tld");
   }
+
+  @Override
+  public ImmutableList<SqlEntity> toSqlEntities() {
+    return ImmutableList.of(); // not persisted in SQL
+  }
 }

core/src/main/java/google/registry/model/common/TimeOfYear.java

@@ -29,20 +29,22 @@ import com.googlecode.objectify.annotation.Embed;
 import com.googlecode.objectify.annotation.Index;
 import google.registry.model.ImmutableObject;
 import java.util.List;
+import javax.persistence.Embeddable;
 import org.joda.time.DateTime;
 
 /**
  * A time of year (month, day, millis of day) that can be stored in a sort-friendly format.
  *
- * <p>This is conceptually similar to {@code MonthDay} in Joda or more generally to Joda's
- * {@code Partial}, but the parts we need are too simple to justify a full implementation of
- * {@code Partial}.
+ * <p>This is conceptually similar to {@code MonthDay} in Joda or more generally to Joda's {@code
+ * Partial}, but the parts we need are too simple to justify a full implementation of {@code
+ * Partial}.
  *
  * <p>For simplicity, the native representation of this class's data is its stored format. This
  * allows it to be embeddable with no translation needed and also delays parsing of the string on
  * load until it's actually needed.
  */
 @Embed
+@Embeddable
 public class TimeOfYear extends ImmutableObject {
 
   /**

core/src/main/java/google/registry/model/contact/ContactCommand.java

@@ -37,7 +37,7 @@ import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
 /** A collection of {@link ContactResource} commands. */
 public class ContactCommand {
 
-  /** The fields on "chgType" from {@link "http://tools.ietf.org/html/rfc5733"}. */
+  /** The fields on "chgType" from <a href="http://tools.ietf.org/html/rfc5733">RFC5733</a>. */
   @XmlTransient
   public static class ContactCreateOrChange extends ImmutableObject
       implements ResourceCreateOrChange<ContactResource.Builder> {
@@ -111,8 +111,8 @@ public class ContactCommand {
   }
 
   /**
-   * A create command for a {@link ContactResource}, mapping "createType" from
-   * {@link "http://tools.ietf.org/html/rfc5733"}.
+   * A create command for a {@link ContactResource}, mapping "createType" from <a
+   * href="http://tools.ietf.org/html/rfc5733">RFC5733</a>}.
    */
   @XmlType(propOrder = {"contactId", "postalInfo", "voice", "fax", "email", "authInfo", "disclose"})
   @XmlRootElement

core/src/main/java/google/registry/model/contact/ContactResource.java

@@ -19,6 +19,7 @@ import static com.google.common.collect.ImmutableList.toImmutableList;
 import static google.registry.model.EppResourceUtils.projectResourceOntoBuilderAtTime;
 
 import com.google.common.collect.ImmutableList;
+import com.googlecode.objectify.Key;
 import com.googlecode.objectify.annotation.Entity;
 import com.googlecode.objectify.annotation.IgnoreSave;
 import com.googlecode.objectify.annotation.Index;
@@ -30,6 +31,9 @@ import google.registry.model.annotations.ExternalMessagingName;
 import google.registry.model.annotations.ReportedOn;
 import google.registry.model.contact.PostalInfo.Type;
 import google.registry.model.transfer.TransferData;
+import google.registry.persistence.VKey;
+import google.registry.persistence.WithStringVKey;
+import google.registry.schema.replay.DatastoreAndSqlEntity;
 import java.util.Objects;
 import java.util.Optional;
 import java.util.stream.Stream;
@@ -59,8 +63,9 @@ import org.joda.time.DateTime;
       @javax.persistence.Index(columnList = "searchName")
     })
 @ExternalMessagingName("contact")
+@WithStringVKey
 public class ContactResource extends EppResource
-    implements ForeignKeyedEppResource, ResourceWithTransferData {
+    implements DatastoreAndSqlEntity, ForeignKeyedEppResource, ResourceWithTransferData {
 
   /**
    * Unique identifier for this contact.
@@ -192,6 +197,10 @@ public class ContactResource extends EppResource
   })
   Disclose disclose;
 
+  public VKey<ContactResource> createVKey() {
+    return VKey.createOfy(ContactResource.class, Key.create(this));
+  }
+
   public String getContactId() {
     return contactId;
   }

core/src/main/java/google/registry/model/contact/Disclose.java

@@ -27,7 +27,7 @@ import javax.persistence.Embedded;
 import javax.xml.bind.annotation.XmlAttribute;
 import javax.xml.bind.annotation.XmlType;
 
-/** The "discloseType" from {@link "http://tools.ietf.org/html/rfc5733"}. */
+/** The "discloseType" from <a href="http://tools.ietf.org/html/rfc5733">RFC5733</a>. */
 @Embed
 @Embeddable
 @XmlType(propOrder = {"name", "org", "addr", "voice", "fax", "email"})
@@ -76,7 +76,7 @@ public class Disclose extends ImmutableObject {
     return flag;
   }
 
-  /** The "intLocType" from {@link "http://tools.ietf.org/html/rfc5733"}. */
+  /** The "intLocType" from <a href="http://tools.ietf.org/html/rfc5733">RFC5733</a>. */
   @Embed
   public static class PostalInfoChoice extends ImmutableObject {
     @XmlAttribute

core/src/main/java/google/registry/model/contact/PostalInfo.java

@@ -32,8 +32,8 @@ import javax.xml.bind.annotation.adapters.NormalizedStringAdapter;
 import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
 
 /**
- * Implementation of both "postalInfoType" and "chgPostalInfoType" from {@link
- * "http://tools.ietf.org/html/rfc5733"}.
+ * Implementation of both "postalInfoType" and "chgPostalInfoType" from <a href=
+ * "http://tools.ietf.org/html/rfc5733">RFC5733</a>.
  */
 @Embed
 @Embeddable

core/src/main/java/google/registry/model/domain/DesignatedContact.java

@@ -18,9 +18,11 @@ import static google.registry.util.PreconditionsUtils.checkArgumentNotNull;
 
 import com.googlecode.objectify.Key;
 import com.googlecode.objectify.annotation.Embed;
+import com.googlecode.objectify.annotation.Ignore;
 import com.googlecode.objectify.annotation.Index;
 import google.registry.model.ImmutableObject;
 import google.registry.model.contact.ContactResource;
+import google.registry.persistence.VKey;
 import javax.persistence.Embeddable;
 import javax.xml.bind.annotation.XmlEnumValue;
 
@@ -36,6 +38,9 @@ import javax.xml.bind.annotation.XmlEnumValue;
  * situation with hosts where client-side renames would make that data stale. However, we sometimes
  * rename contacts internally ourselves, and it's easier to use the same model for both cases.
  *
+ * <p>This entity type is not persisted in Cloud SQL. The different roles are represented as
+ * separate fields in the Domain table.
+ *
  * @see <a href="http://tools.ietf.org/html/rfc5731#section-2.2">RFC 5731 - EPP Domain Name Mapping
  *     - Contact and Client Identifiers</a>
  */
@@ -58,22 +63,28 @@ public class DesignatedContact extends ImmutableObject {
     REGISTRANT
   }
 
-  public static DesignatedContact create(Type type, Key<ContactResource> contact) {
+  public static DesignatedContact create(Type type, VKey<ContactResource> contact) {
     DesignatedContact instance = new DesignatedContact();
     instance.type = type;
-    instance.contact = checkArgumentNotNull(contact, "Must specify contact key");
+    instance.contactVKey = checkArgumentNotNull(contact, "Must specify contact key");
+    instance.contact = contact.maybeGetOfyKey().orElse(null);
     return instance;
   }
 
   Type type;
 
   @Index Key<ContactResource> contact;
+  @Ignore VKey<ContactResource> contactVKey;
 
   public Type getType() {
     return type;
   }
 
-  public Key<ContactResource> getContactKey() {
-    return contact;
+  public VKey<ContactResource> getContactKey() {
+    return contactVKey;
+  }
+
+  public DesignatedContact reconstitute() {
+    return create(type, VKey.createOfy(ContactResource.class, contact));
   }
 }

core/src/main/java/google/registry/model/domain/DomainBase.java

@@ -77,10 +77,10 @@ import javax.annotation.Nullable;
 import javax.persistence.AttributeOverride;
 import javax.persistence.AttributeOverrides;
 import javax.persistence.Column;
-import javax.persistence.Convert;
 import javax.persistence.ElementCollection;
 import javax.persistence.Embedded;
 import javax.persistence.JoinTable;
+import javax.persistence.PostLoad;
 import javax.persistence.Transient;
 import org.joda.time.DateTime;
 import org.joda.time.Interval;
@@ -108,7 +108,7 @@ import org.joda.time.Interval;
     })
 @ExternalMessagingName("domain")
 public class DomainBase extends EppResource
-    implements ForeignKeyedEppResource, ResourceWithTransferData, DatastoreAndSqlEntity {
+    implements DatastoreAndSqlEntity, ForeignKeyedEppResource, ResourceWithTransferData {
 
   /** The max number of years that a domain can be registered for, as set by ICANN policy. */
   public static final int MAX_REGISTRATION_YEARS = 10;
@@ -136,19 +136,11 @@ public class DomainBase extends EppResource
   @Index
   String tld;
 
-  /**
-   * References to hosts that are the nameservers for the domain.
-   *
-   * <p>This is a legacy field: we have to preserve it because it is still persisted and indexed in
-   * the datastore, but all external references go through nsHostVKeys.
-   */
-  @Index @ElementCollection @Transient Set<Key<HostResource>> nsHosts;
-
-  @Ignore
+  /** References to hosts that are the nameservers for the domain. */
+  @Index
   @ElementCollection
   @JoinTable(name = "DomainHost")
-  @Convert(converter = HostResource.VKeyHostResourceConverter.class)
-  Set<VKey<HostResource>> nsHostVKeys;
+  Set<VKey<HostResource>> nsHosts;
 
   /**
    * The union of the contacts visible via {@link #getContacts} and {@link #getRegistrant}.
@@ -157,6 +149,17 @@ public class DomainBase extends EppResource
    */
   @Transient Set<DesignatedContact> allContacts;
 
+  /**
+   * Contacts as they are stored in cloud SQL.
+   *
+   * <p>This information is duplicated in allContacts, and must be kept in sync with it.
+   */
+  @Ignore VKey<ContactResource> adminContact;
+
+  @Ignore VKey<ContactResource> billingContact;
+  @Ignore VKey<ContactResource> techContact;
+  @Ignore VKey<ContactResource> registrantContact;
+
   /** Authorization info (aka transfer secret) of the domain. */
   @Embedded
   @AttributeOverrides({
@@ -259,10 +262,33 @@ public class DomainBase extends EppResource
 
   @OnLoad
   void load() {
-    nsHostVKeys =
-        nullToEmptyImmutableCopy(nsHosts).stream()
-            .map(hostKey -> VKey.createOfy(HostResource.class, hostKey))
-            .collect(toImmutableSet());
+    // Reconstitute all of the contacts so that they have VKeys.
+    allContacts =
+        allContacts.stream().map(contact -> contact.reconstitute()).collect(toImmutableSet());
+    setContactFields(allContacts, true);
+  }
+
+  @PostLoad
+  void postLoad() {
+    // Reconstitute the contact list.
+    ImmutableSet.Builder<DesignatedContact> contactsBuilder =
+        new ImmutableSet.Builder<DesignatedContact>();
+
+    if (registrantContact != null) {
+      contactsBuilder.add(
+          DesignatedContact.create(DesignatedContact.Type.REGISTRANT, registrantContact));
+    }
+    if (billingContact != null) {
+      contactsBuilder.add(DesignatedContact.create(DesignatedContact.Type.BILLING, billingContact));
+    }
+    if (techContact != null) {
+      contactsBuilder.add(DesignatedContact.create(DesignatedContact.Type.TECH, techContact));
+    }
+    if (adminContact != null) {
+      contactsBuilder.add(DesignatedContact.create(DesignatedContact.Type.ADMIN, adminContact));
+    }
+
+    allContacts = contactsBuilder.build();
   }
 
   public ImmutableSet<String> getSubordinateHosts() {
@@ -325,9 +351,7 @@ public class DomainBase extends EppResource
   }
 
   public ImmutableSet<VKey<HostResource>> getNameservers() {
-    // Since nsHostVKeys gets initialized both from setNameservers() and the OnLoad method, this
-    // should always be valid.
-    return nullToEmptyImmutableCopy(nsHostVKeys);
+    return nullToEmptyImmutableCopy(nsHosts);
   }
 
   public final String getCurrentSponsorClientId() {
@@ -517,13 +541,20 @@ public class DomainBase extends EppResource
   }
 
   /** A key to the registrant who registered this domain. */
-  public Key<ContactResource> getRegistrant() {
-    return nullToEmpty(allContacts)
-        .stream()
-        .filter(IS_REGISTRANT)
-        .findFirst()
-        .get()
-        .getContactKey();
+  public VKey<ContactResource> getRegistrant() {
+    return registrantContact;
+  }
+
+  public VKey<ContactResource> getAdminContact() {
+    return adminContact;
+  }
+
+  public VKey<ContactResource> getBillingContact() {
+    return billingContact;
+  }
+
+  public VKey<ContactResource> getTechContact() {
+    return techContact;
   }
 
   /** Associated contacts for the domain (other than registrant). */
@@ -539,7 +570,7 @@ public class DomainBase extends EppResource
   }
 
   /** Returns all referenced contacts from this domain or application. */
-  public ImmutableSet<Key<ContactResource>> getReferencedContacts() {
+  public ImmutableSet<VKey<ContactResource>> getReferencedContacts() {
     return nullToEmptyImmutableCopy(allContacts)
         .stream()
         .map(DesignatedContact::getContactKey)
@@ -551,6 +582,37 @@ public class DomainBase extends EppResource
     return tld;
   }
 
+  /**
+   * Sets the individual contact fields from {@code contacts}.
+   *
+   * <p>The registrant field is only set if {@code includeRegistrant} is true, as this field needs
+   * to be set in some circumstances but not in others.
+   */
+  private void setContactFields(Set<DesignatedContact> contacts, boolean includeRegistrant) {
+
+    // Set the individual contact fields.
+    for (DesignatedContact contact : contacts) {
+      switch (contact.getType()) {
+        case BILLING:
+          billingContact = contact.getContactKey();
+          break;
+        case TECH:
+          techContact = contact.getContactKey();
+          break;
+        case ADMIN:
+          adminContact = contact.getContactKey();
+          break;
+        case REGISTRANT:
+          if (includeRegistrant) {
+            registrantContact = contact.getContactKey();
+          }
+          break;
+        default:
+          throw new IllegalArgumentException("Unknown contact resource type: " + contact.getType());
+      }
+    }
+  }
+
   /** Predicate to determine if a given {@link DesignatedContact} is the registrant. */
   private static final Predicate<DesignatedContact> IS_REGISTRANT =
       (DesignatedContact contact) -> DesignatedContact.Type.REGISTRANT.equals(contact.type);
@@ -569,14 +631,6 @@ public class DomainBase extends EppResource
 
     Builder(DomainBase instance) {
       super(instance);
-
-      // Convert nsHosts to nsHostVKeys.
-      if (instance.nsHosts != null) {
-        instance.nsHostVKeys =
-            instance.nsHosts.stream()
-                .map(key -> VKey.createOfy(HostResource.class, key))
-                .collect(toImmutableSet());
-      }
     }
 
     @Override
@@ -595,7 +649,11 @@ public class DomainBase extends EppResource
 
       checkArgumentNotNull(
           emptyToNull(instance.fullyQualifiedDomainName), "Missing fullyQualifiedDomainName");
-      checkArgument(instance.allContacts.stream().anyMatch(IS_REGISTRANT), "Missing registrant");
+      if (instance.getRegistrant() == null
+          && instance.allContacts.stream().anyMatch(IS_REGISTRANT)) {
+        throw new IllegalArgumentException("registrant is null but is in allContacts");
+      }
+      checkArgumentNotNull(instance.getRegistrant(), "Missing registrant");
       instance.tld = getTldFromDomainName(instance.fullyQualifiedDomainName);
       return super.build();
     }
@@ -613,11 +671,14 @@ public class DomainBase extends EppResource
       return thisCastToDerived();
     }
 
-    public Builder setRegistrant(Key<ContactResource> registrant) {
+    public Builder setRegistrant(VKey<ContactResource> registrant) {
       // Replace the registrant contact inside allContacts.
       getInstance().allContacts = union(
           getInstance().getContacts(),
           DesignatedContact.create(Type.REGISTRANT, checkArgumentNotNull(registrant)));
+
+      // Set the registrant field specifically.
+      getInstance().registrantContact = registrant;
       return thisCastToDerived();
     }
 
@@ -627,27 +688,12 @@ public class DomainBase extends EppResource
     }
 
     public Builder setNameservers(VKey<HostResource> nameserver) {
-      Optional<Key<HostResource>> nsKey = nameserver.maybeGetOfyKey();
-      if (nsKey.isPresent()) {
-        getInstance().nsHosts = ImmutableSet.of(nsKey.get());
-      } else {
-        getInstance().nsHosts = null;
-      }
-      getInstance().nsHostVKeys = ImmutableSet.of(nameserver);
+      getInstance().nsHosts = ImmutableSet.of(nameserver);
       return thisCastToDerived();
     }
 
     public Builder setNameservers(ImmutableSet<VKey<HostResource>> nameservers) {
-      // If we have all of the ofy keys, we can set nsHosts.  Otherwise, make it null.
-      if (nameservers != null
-          && nameservers.stream().allMatch(key -> key.maybeGetOfyKey().isPresent())) {
-        getInstance().nsHosts =
-            nameservers.stream().map(key -> key.getOfyKey()).collect(toImmutableSet());
-      } else {
-        getInstance().nsHosts = null;
-      }
-
-      getInstance().nsHostVKeys = forceEmptyToNull(nameservers);
+      getInstance().nsHosts = forceEmptyToNull(nameservers);
       return thisCastToDerived();
     }
 
@@ -675,12 +721,16 @@ public class DomainBase extends EppResource
 
     public Builder setContacts(ImmutableSet<DesignatedContact> contacts) {
       checkArgument(contacts.stream().noneMatch(IS_REGISTRANT), "Registrant cannot be a contact");
+
       // Replace the non-registrant contacts inside allContacts.
       getInstance().allContacts =
           Streams.concat(
                   nullToEmpty(getInstance().allContacts).stream().filter(IS_REGISTRANT),
                   contacts.stream())
               .collect(toImmutableSet());
+
+      // Set the individual fields.
+      getInstance().setContactFields(contacts, false);
       return thisCastToDerived();
     }
 

core/src/main/java/google/registry/model/domain/DomainCommand.java

@@ -41,6 +41,7 @@ import google.registry.model.eppinput.ResourceCommand.ResourceUpdate;
 import google.registry.model.eppinput.ResourceCommand.SingleResourceCommand;
 import google.registry.model.host.HostResource;
 import google.registry.model.index.ForeignKeyIndex;
+import google.registry.persistence.VKey;
 import java.util.Map;
 import java.util.Set;
 import javax.annotation.Nullable;
@@ -71,10 +72,10 @@ public class DomainCommand {
     T cloneAndLinkReferences(DateTime now) throws InvalidReferencesException;
   }
 
-  /** The fields on "chgType" from {@link "http://tools.ietf.org/html/rfc5731"}. */
+  /** The fields on "chgType" from <a href="http://tools.ietf.org/html/rfc5731">RFC5731</a>. */
   @XmlTransient
-  public static class DomainCreateOrChange<B extends DomainBase.Builder>
-      extends ImmutableObject implements ResourceCreateOrChange<B> {
+  public static class DomainCreateOrChange<B extends DomainBase.Builder> extends ImmutableObject
+      implements ResourceCreateOrChange<B> {
 
     /** The contactId of the registrant who registered this domain. */
     @XmlElement(name = "registrant")
@@ -102,19 +103,20 @@ public class DomainCommand {
   }
 
   /**
-   * A create command for a {@link DomainBase}, mapping "createType" from
-   * {@link "http://tools.ietf.org/html/rfc5731"}.
+   * A create command for a {@link DomainBase}, mapping "createType" from <a
+   * href="http://tools.ietf.org/html/rfc5731">RFC5731</a>.
    */
   @XmlRootElement
-  @XmlType(propOrder = {
-      "fullyQualifiedDomainName",
-      "period",
-      "nameserverFullyQualifiedHostNames",
-      "registrantContactId",
-      "foreignKeyedDesignatedContacts",
-      "authInfo"})
-  public static class Create
-      extends DomainCreateOrChange<DomainBase.Builder>
+  @XmlType(
+      propOrder = {
+        "fullyQualifiedDomainName",
+        "period",
+        "nameserverFullyQualifiedHostNames",
+        "registrantContactId",
+        "foreignKeyedDesignatedContacts",
+        "authInfo"
+      })
+  public static class Create extends DomainCreateOrChange<DomainBase.Builder>
       implements CreateOrUpdate<Create> {
 
     /** Fully qualified domain name, which serves as a unique identifier for this domain. */
@@ -188,7 +190,7 @@ public class DomainCommand {
             now);
         for (DesignatedContact contact : contacts) {
           if (DesignatedContact.Type.REGISTRANT.equals(contact.getType())) {
-            clone.registrant = contact.getContactKey();
+            clone.registrant = contact.getContactKey().getOfyKey();
             clone.contacts = forceEmptyToNull(difference(contacts, contact));
             break;
           }
@@ -439,8 +441,10 @@ public class DomainCommand {
         loadByForeignKeysCached(foreignKeys.build(), ContactResource.class, now);
     ImmutableSet.Builder<DesignatedContact> linkedContacts = new ImmutableSet.Builder<>();
     for (ForeignKeyedDesignatedContact contact : contacts) {
-      linkedContacts.add(DesignatedContact.create(
-          contact.type, loadedContacts.get(contact.contactId)));
+      linkedContacts.add(
+          DesignatedContact.create(
+              contact.type,
+              VKey.createOfy(ContactResource.class, loadedContacts.get(contact.contactId))));
     }
     return linkedContacts.build();
   }

core/src/main/java/google/registry/model/domain/Period.java

@@ -20,7 +20,7 @@ import javax.xml.bind.annotation.XmlAttribute;
 import javax.xml.bind.annotation.XmlEnumValue;
 import javax.xml.bind.annotation.XmlValue;
 
-/** The "periodType" from {@link "http://tools.ietf.org/html/rfc5731"}. */
+/** The "periodType" from <a href="http://tools.ietf.org/html/rfc5731">RFC5731</a>. */
 @Embed
 @javax.persistence.Embeddable
 public class Period extends ImmutableObject {

core/src/main/java/google/registry/model/domain/fee12/FeeCheckCommandExtensionItemV12.java

@@ -29,11 +29,13 @@ import org.joda.time.DateTime;
  * An individual price check item in version 0.12 of the fee extension on domain check commands.
  * Items look like:
  *
+ * <pre>{@code
  * <fee:command name="renew" phase="sunrise" subphase="hello">
  *   <fee:period unit="y">1</fee:period>
  *   <fee:class>premium</fee:class>
  *   <fee:date>2017-05-17T13:22:21.0Z</fee:date>
  * </fee:command>
+ * }</pre>
  *
  * In a change from previous versions of the extension, items do not contain domain names; instead,
  * the names from the non-extension check element are used.

core/src/main/java/google/registry/model/domain/launch/LaunchNotice.java

@@ -95,9 +95,6 @@ public class LaunchNotice extends ImmutableObject {
 
   /**
    * Validate the checksum of the notice against the domain label.
-   *
-   * @throws IllegalArgumentException
-   * @throws InvalidChecksumException
    */
   public void validate(String domainLabel) throws InvalidChecksumException {
     // According to http://tools.ietf.org/html/draft-lozano-tmch-func-spec-08#section-6.3, a TCNID

core/src/main/java/google/registry/model/domain/rgp/GracePeriodStatus.java

@@ -49,9 +49,9 @@ public enum GracePeriodStatus implements EppEnum {
   AUTO_RENEW("autoRenewPeriod"),
 
   /**
-   * This status value is used to describe a domain for which a <delete> command has been received,
-   * but the domain has not yet been purged because an opportunity exists to restore the domain and
-   * abort the deletion process.
+   * This status value is used to describe a domain for which a &lt;delete&gt; command has been
+   * received, but the domain has not yet been purged because an opportunity exists to restore the
+   * domain and abort the deletion process.
    */
   REDEMPTION("redemptionPeriod"),
 

core/src/main/java/google/registry/model/domain/token/AllocationToken.java

@@ -45,6 +45,8 @@ import google.registry.model.common.TimedTransitionProperty;
 import google.registry.model.common.TimedTransitionProperty.TimeMapper;
 import google.registry.model.common.TimedTransitionProperty.TimedTransition;
 import google.registry.model.reporting.HistoryEntry;
+import google.registry.persistence.VKey;
+import google.registry.persistence.WithStringVKey;
 import java.util.Optional;
 import java.util.Set;
 import javax.annotation.Nullable;
@@ -53,6 +55,7 @@ import org.joda.time.DateTime;
 /** An entity representing an allocation token. */
 @ReportedOn
 @Entity
+@WithStringVKey
 public class AllocationToken extends BackupGroupRoot implements Buildable {
 
   // Promotions should only move forward, and ENDED / CANCELLED are terminal states.
@@ -179,6 +182,10 @@ public class AllocationToken extends BackupGroupRoot implements Buildable {
     return tokenStatusTransitions;
   }
 
+  public VKey<AllocationToken> createVKey() {
+    return VKey.createOfy(getClass(), Key.create(this));
+  }
+
   @Override
   public Builder asBuilder() {
     return new Builder(clone(this));

core/src/main/java/google/registry/model/domain/token/AllocationTokenExtension.java

@@ -25,7 +25,7 @@ import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
  * An allocation token extension that may be present on EPP domain commands.
  *
  * @see <a href="https://tools.ietf.org/html/draft-ietf-regext-allocation-token-04">the IETF
- *     draft</a> for full details.
+ *     draft</a>
  */
 @XmlRootElement(name = "allocationToken")
 public class AllocationTokenExtension extends ImmutableObject implements CommandExtension {

core/src/main/java/google/registry/model/eppcommon/Address.java

@@ -44,8 +44,9 @@ import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
 /**
  * Container for generic street address.
  *
- * <p>This is the "addrType" type from {@link "http://tools.ietf.org/html/rfc5733"}. It also matches
- * the "addrType" type from {@link "http://tools.ietf.org/html/draft-lozano-tmch-smd"}.
+ * <p>This is the "addrType" type from <a href="http://tools.ietf.org/html/rfc5733">RFC5733</a>. It
+ * also matches the "addrType" type from <a
+ * href="http://tools.ietf.org/html/draft-lozano-tmch-smd">Mark and Signed Mark Objects Mapping</a>.
  *
  * @see google.registry.model.contact.ContactAddress
  * @see google.registry.model.mark.MarkAddress

core/src/main/java/google/registry/model/eppcommon/PhoneNumber.java

@@ -29,8 +29,9 @@ import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
 /**
  * Container for generic E164 phone number.
  *
- * <p>This is the "e164" type from {@link "http://tools.ietf.org/html/rfc5733"}. It also matches the
- * "e164Type" type from {@link "http://tools.ietf.org/html/draft-lozano-tmch-smd"}.
+ * <p>This is the "e164" type from <a href="http://tools.ietf.org/html/rfc5733">RFC5733</a>. It also
+ * matches the "e164Type" type from <a href="http://tools.ietf.org/html/draft-lozano-tmch-smd">Mark
+ * and Signed Mark Objects Mapping</a>
  *
  * <blockquote>
  *

core/src/main/java/google/registry/model/eppoutput/Greeting.java

@@ -24,7 +24,7 @@ import javax.xml.bind.annotation.XmlElementWrapper;
 import org.joda.time.DateTime;
 
 /**
- * A greeting, defined in {@link "http://tools.ietf.org/html/rfc5730"}.
+ * A greeting, defined in <a href="http://tools.ietf.org/html/rfc5730">RFC5730</a>.
  *
  * <p>It would be nice to make this a singleton, but we need the {@link #svDate} field to stay
  * current.

core/src/main/java/google/registry/model/host/HostCommand.java

@@ -32,7 +32,7 @@ import javax.xml.bind.annotation.XmlType;
 /** A collection of {@link HostResource} commands. */
 public class HostCommand {
 
-  /** The fields on "chgType" from {@link "http://tools.ietf.org/html/rfc5732"}. */
+  /** The fields on "chgType" from <a href="http://tools.ietf.org/html/rfc5732">RFC5732</a>. */
   @XmlTransient
   abstract static class HostCreateOrChange extends AbstractSingleResourceCommand
       implements ResourceCreateOrChange<HostResource.Builder> {
@@ -42,13 +42,13 @@ public class HostCommand {
   }
 
   /**
-   * A create command for a {@link HostResource}, mapping "createType" from
-   * {@link "http://tools.ietf.org/html/rfc5732"}.
+   * A create command for a {@link HostResource}, mapping "createType" from <a
+   * href="http://tools.ietf.org/html/rfc5732">RFC5732</a>.
    */
-  @XmlType(propOrder = {"targetId", "inetAddresses" })
+  @XmlType(propOrder = {"targetId", "inetAddresses"})
   @XmlRootElement
-  public static class Create
-      extends HostCreateOrChange implements ResourceCreateOrChange<HostResource.Builder> {
+  public static class Create extends HostCreateOrChange
+      implements ResourceCreateOrChange<HostResource.Builder> {
     /** IP Addresses for this host. Can be null if this is an external host. */
     @XmlElement(name = "addr")
     Set<InetAddress> inetAddresses;

core/src/main/java/google/registry/model/host/HostResource.java

@@ -34,7 +34,8 @@ import google.registry.model.annotations.ReportedOn;
 import google.registry.model.domain.DomainBase;
 import google.registry.model.transfer.TransferData;
 import google.registry.persistence.VKey;
-import google.registry.persistence.converter.VKeyConverter;
+import google.registry.persistence.WithStringVKey;
+import google.registry.schema.replay.DatastoreAndSqlEntity;
 import java.net.InetAddress;
 import java.util.Optional;
 import java.util.Set;
@@ -54,7 +55,9 @@ import org.joda.time.DateTime;
 @Entity
 @javax.persistence.Entity
 @ExternalMessagingName("host")
-public class HostResource extends EppResource implements ForeignKeyedEppResource {
+@WithStringVKey
+public class HostResource extends EppResource
+    implements DatastoreAndSqlEntity, ForeignKeyedEppResource {
 
   /**
    * Fully qualified hostname, which is a unique identifier for this host.
@@ -212,11 +215,4 @@ public class HostResource extends EppResource implements ForeignKeyedEppResource
       return this;
     }
   }
-
-  public static class VKeyHostResourceConverter extends VKeyConverter<HostResource> {
-    @Override
-    protected Class<HostResource> getAttributeClass() {
-      return HostResource.class;
-    }
-  }
 }

core/src/main/java/google/registry/model/ofy/CommitLogBucket.java

@@ -22,6 +22,7 @@ import static google.registry.model.ofy.ObjectifyService.ofy;
 import static google.registry.util.DateTimeUtils.START_OF_TIME;
 
 import com.google.common.collect.ContiguousSet;
+import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.ImmutableSortedSet;
 import com.google.common.collect.Range;
@@ -33,6 +34,8 @@ import google.registry.model.Buildable;
 import google.registry.model.ImmutableObject;
 import google.registry.model.annotations.NotBackedUp;
 import google.registry.model.annotations.NotBackedUp.Reason;
+import google.registry.schema.replay.DatastoreEntity;
+import google.registry.schema.replay.SqlEntity;
 import google.registry.util.NonFinalForTesting;
 import java.util.Random;
 import java.util.function.Supplier;
@@ -51,7 +54,7 @@ import org.joda.time.DateTime;
  */
 @Entity
 @NotBackedUp(reason = Reason.COMMIT_LOGS)
-public class CommitLogBucket extends ImmutableObject implements Buildable {
+public class CommitLogBucket extends ImmutableObject implements Buildable, DatastoreEntity {
 
   /**
    * Ranges from 1 to {@link RegistryConfig#getCommitLogBucketCount()}, inclusive; starts at 1 since
@@ -70,6 +73,11 @@ public class CommitLogBucket extends ImmutableObject implements Buildable {
     return lastWrittenTime;
   }
 
+  @Override
+  public ImmutableList<SqlEntity> toSqlEntities() {
+    return ImmutableList.of(); // not persisted in SQL
+  }
+
   /**
    * Returns the key for the specified bucket ID.
    *

core/src/main/java/google/registry/model/ofy/CommitLogCheckpoint.java

@@ -27,6 +27,8 @@ import com.googlecode.objectify.annotation.Parent;
 import google.registry.model.ImmutableObject;
 import google.registry.model.annotations.NotBackedUp;
 import google.registry.model.annotations.NotBackedUp.Reason;
+import google.registry.schema.replay.DatastoreEntity;
+import google.registry.schema.replay.SqlEntity;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Objects;
@@ -44,7 +46,7 @@ import org.joda.time.DateTime;
  */
 @Entity
 @NotBackedUp(reason = Reason.COMMIT_LOGS)
-public class CommitLogCheckpoint extends ImmutableObject {
+public class CommitLogCheckpoint extends ImmutableObject implements DatastoreEntity {
 
   /** Shared singleton parent entity for commit log checkpoints. */
   @Parent
@@ -71,6 +73,11 @@ public class CommitLogCheckpoint extends ImmutableObject {
     return builder.build();
   }
 
+  @Override
+  public ImmutableList<SqlEntity> toSqlEntities() {
+    return ImmutableList.of(); // not persisted in SQL
+  }
+
   /**
    * Creates a CommitLogCheckpoint for the given wall time and bucket checkpoint times, specified as
    * a map from bucket ID to bucket commit timestamp.

core/src/main/java/google/registry/model/ofy/CommitLogCheckpointRoot.java

@@ -17,12 +17,15 @@ package google.registry.model.ofy;
 import static google.registry.model.ofy.ObjectifyService.ofy;
 import static google.registry.util.DateTimeUtils.START_OF_TIME;
 
+import com.google.common.collect.ImmutableList;
 import com.googlecode.objectify.Key;
 import com.googlecode.objectify.annotation.Entity;
 import com.googlecode.objectify.annotation.Id;
 import google.registry.model.ImmutableObject;
 import google.registry.model.annotations.NotBackedUp;
 import google.registry.model.annotations.NotBackedUp.Reason;
+import google.registry.schema.replay.DatastoreEntity;
+import google.registry.schema.replay.SqlEntity;
 import org.joda.time.DateTime;
 
 /**
@@ -30,7 +33,7 @@ import org.joda.time.DateTime;
  */
 @Entity
 @NotBackedUp(reason = Reason.COMMIT_LOGS)
-public class CommitLogCheckpointRoot extends ImmutableObject {
+public class CommitLogCheckpointRoot extends ImmutableObject implements DatastoreEntity {
 
   public static final long SINGLETON_ID = 1;  // There is always exactly one of these.
 
@@ -49,6 +52,11 @@ public class CommitLogCheckpointRoot extends ImmutableObject {
     return lastWrittenTime;
   }
 
+  @Override
+  public ImmutableList<SqlEntity> toSqlEntities() {
+    return ImmutableList.of(); // not persisted in SQL
+  }
+
   public static CommitLogCheckpointRoot loadRoot() {
     CommitLogCheckpointRoot root = ofy().load().key(getKey()).now();
     return root == null ? new CommitLogCheckpointRoot() : root;

core/src/main/java/google/registry/model/ofy/CommitLogManifest.java

@@ -17,6 +17,7 @@ package google.registry.model.ofy;
 import static google.registry.util.CollectionUtils.nullToEmptyImmutableCopy;
 import static org.joda.time.DateTimeZone.UTC;
 
+import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
 import com.googlecode.objectify.Key;
 import com.googlecode.objectify.annotation.Entity;
@@ -25,6 +26,8 @@ import com.googlecode.objectify.annotation.Parent;
 import google.registry.model.ImmutableObject;
 import google.registry.model.annotations.NotBackedUp;
 import google.registry.model.annotations.NotBackedUp.Reason;
+import google.registry.schema.replay.DatastoreEntity;
+import google.registry.schema.replay.SqlEntity;
 import java.util.LinkedHashSet;
 import java.util.Set;
 import org.joda.time.DateTime;
@@ -38,7 +41,7 @@ import org.joda.time.DateTime;
  */
 @Entity
 @NotBackedUp(reason = Reason.COMMIT_LOGS)
-public class CommitLogManifest extends ImmutableObject {
+public class CommitLogManifest extends ImmutableObject implements DatastoreEntity {
 
   /** Commit log manifests are parented on a random bucket. */
   @Parent
@@ -67,6 +70,11 @@ public class CommitLogManifest extends ImmutableObject {
     return nullToEmptyImmutableCopy(deletions);
   }
 
+  @Override
+  public ImmutableList<SqlEntity> toSqlEntities() {
+    return ImmutableList.of(); // not persisted in SQL
+  }
+
   public static CommitLogManifest create(
       Key<CommitLogBucket> parent, DateTime commitTime, Set<Key<?>> deletions) {
     CommitLogManifest instance = new CommitLogManifest();

core/src/main/java/google/registry/model/ofy/CommitLogMutation.java

@@ -21,6 +21,7 @@ import static google.registry.model.ofy.ObjectifyService.ofy;
 
 import com.google.appengine.api.datastore.KeyFactory;
 import com.google.common.annotations.VisibleForTesting;
+import com.google.common.collect.ImmutableList;
 import com.googlecode.objectify.Key;
 import com.googlecode.objectify.annotation.Entity;
 import com.googlecode.objectify.annotation.Id;
@@ -28,11 +29,13 @@ import com.googlecode.objectify.annotation.Parent;
 import google.registry.model.ImmutableObject;
 import google.registry.model.annotations.NotBackedUp;
 import google.registry.model.annotations.NotBackedUp.Reason;
+import google.registry.schema.replay.DatastoreEntity;
+import google.registry.schema.replay.SqlEntity;
 
 /** Representation of a saved entity in a {@link CommitLogManifest} (not deletes). */
 @Entity
 @NotBackedUp(reason = Reason.COMMIT_LOGS)
-public class CommitLogMutation extends ImmutableObject {
+public class CommitLogMutation extends ImmutableObject implements DatastoreEntity {
 
   /** The manifest this belongs to. */
   @Parent
@@ -58,6 +61,11 @@ public class CommitLogMutation extends ImmutableObject {
     return createFromPbBytes(entityProtoBytes);
   }
 
+  @Override
+  public ImmutableList<SqlEntity> toSqlEntities() {
+    return ImmutableList.of(); // not persisted in SQL
+  }
+
   /**
    * Returns a new mutation entity created from an @Entity ImmutableObject instance.
    *

core/src/main/java/google/registry/model/ofy/DatastoreTransactionManager.java

@@ -15,6 +15,7 @@
 package google.registry.model.ofy;
 
 import static google.registry.model.ofy.ObjectifyService.ofy;
+import static google.registry.util.PreconditionsUtils.checkArgumentNotNull;
 
 import com.google.common.collect.ImmutableCollection;
 import com.google.common.collect.ImmutableList;
@@ -22,6 +23,7 @@ import com.googlecode.objectify.Key;
 import google.registry.persistence.VKey;
 import google.registry.persistence.transaction.TransactionManager;
 import java.util.Iterator;
+import java.util.NoSuchElementException;
 import java.util.Optional;
 import java.util.function.Supplier;
 import java.util.stream.StreamSupport;
@@ -93,42 +95,45 @@ public class DatastoreTransactionManager implements TransactionManager {
 
   @Override
   public void saveNew(Object entity) {
-    throw new UnsupportedOperationException("Not available in the Datastore transaction manager");
+    checkArgumentNotNull(entity, "entity must be specified");
+    getOfy().save().entity(entity);
   }
 
   @Override
   public void saveAllNew(ImmutableCollection<?> entities) {
-    throw new UnsupportedOperationException("Not available in the Datastore transaction manager");
+    getOfy().save().entities(entities);
   }
 
   @Override
   public void saveNewOrUpdate(Object entity) {
-    throw new UnsupportedOperationException("Not available in the Datastore transaction manager");
+    checkArgumentNotNull(entity, "entity must be specified");
+    getOfy().save().entity(entity);
   }
 
   @Override
   public void saveNewOrUpdateAll(ImmutableCollection<?> entities) {
-    throw new UnsupportedOperationException("Not available in the Datastore transaction manager");
+    getOfy().save().entities(entities);
   }
 
   @Override
   public void update(Object entity) {
-    throw new UnsupportedOperationException("Not available in the Datastore transaction manager");
+    checkArgumentNotNull(entity, "entity must be specified");
+    getOfy().save().entity(entity);
   }
 
   @Override
   public void updateAll(ImmutableCollection<?> entities) {
-    throw new UnsupportedOperationException("Not available in the Datastore transaction manager");
+    getOfy().save().entities(entities);
   }
 
   @Override
   public boolean checkExists(Object entity) {
-    throw new UnsupportedOperationException("Not available in the Datastore transaction manager");
+    return getOfy().load().key(Key.create(entity)).now() != null;
   }
 
   @Override
   public <T> boolean checkExists(VKey<T> key) {
-    throw new UnsupportedOperationException("Not available in the Datastore transaction manager");
+    return getOfy().load().key(key.getOfyKey()).now() != null;
   }
 
   // TODO: add tests for these methods.  They currently have some degree of test coverage because
@@ -136,8 +141,17 @@ public class DatastoreTransactionManager implements TransactionManager {
   // VKey instead of by ofy Key.  But ideally, there should be one set of TransactionManager
   // interface tests that are applied to both the datastore and SQL implementations.
   @Override
-  public <T> Optional<T> load(VKey<T> key) {
-    return Optional.of(getOfy().load().key(key.getOfyKey()).now());
+  public <T> Optional<T> maybeLoad(VKey<T> key) {
+    return Optional.ofNullable(getOfy().load().key(key.getOfyKey()).now());
+  }
+
+  @Override
+  public <T> T load(VKey<T> key) {
+    T result = getOfy().load().key(key.getOfyKey()).now();
+    if (result == null) {
+      throw new NoSuchElementException(key.toString());
+    }
+    return result;
   }
 
   @Override
@@ -151,16 +165,12 @@ public class DatastoreTransactionManager implements TransactionManager {
 
   @Override
   public <T> ImmutableList<T> loadAll(Class<T> clazz) {
+    // We can do a ofy().load().type(clazz), but this doesn't work in a transaction.
     throw new UnsupportedOperationException("Not available in the Datastore transaction manager");
   }
 
   @Override
-  public <T> int delete(VKey<T> key) {
-    throw new UnsupportedOperationException("Not available in the Datastore transaction manager");
-  }
-
-  @Override
-  public <T> void assertDelete(VKey<T> key) {
-    throw new UnsupportedOperationException("Not available in the Datastore transaction manager");
+  public <T> void delete(VKey<T> key) {
+    getOfy().delete().key(key.getOfyKey()).now();
   }
 }

core/src/main/java/google/registry/model/ofy/ObjectifyService.java

@@ -34,9 +34,9 @@ import com.googlecode.objectify.annotation.EntitySubclass;
 import com.googlecode.objectify.impl.translate.TranslatorFactory;
 import com.googlecode.objectify.impl.translate.opt.joda.MoneyStringTranslatorFactory;
 import google.registry.config.RegistryEnvironment;
+import google.registry.model.Buildable;
 import google.registry.model.EntityClasses;
 import google.registry.model.ImmutableObject;
-import google.registry.model.host.HostResource;
 import google.registry.model.translators.BloomFilterOfStringTranslatorFactory;
 import google.registry.model.translators.CidrAddressBlockTranslatorFactory;
 import google.registry.model.translators.CommitLogRevisionsTranslatorFactory;
@@ -130,7 +130,7 @@ public class ObjectifyService {
             new InetAddressTranslatorFactory(),
             new MoneyStringTranslatorFactory(),
             new ReadableInstantUtcTranslatorFactory(),
-            new VKeyTranslatorFactory<HostResource>(HostResource.class),
+            new VKeyTranslatorFactory(),
             new UpdateAutoTimestampTranslatorFactory())) {
       factory().getTranslators().add(translatorFactory);
     }
@@ -151,11 +151,14 @@ public class ObjectifyService {
       String kind = Key.getKind(clazz);
       boolean registered = factory().getMetadata(kind) != null;
       if (clazz.isAnnotationPresent(Entity.class)) {
-        // Objectify silently ignores re-registrations for a given kind string, even if the classes
-        // being registered are distinct. Throw an exception if that would happen here.
-        checkState(!registered,
+        // Objectify silently replaces current registration for a given kind string when a different
+        // class is registered again for this kind. For simplicity's sake, throw an exception on any
+        // re-registration.
+        checkState(
+            !registered,
             "Kind '%s' already registered, cannot register new @Entity %s",
-            kind, clazz.getCanonicalName());
+            kind,
+            clazz.getCanonicalName());
       } else if (clazz.isAnnotationPresent(EntitySubclass.class)) {
         // Ensure that any @EntitySubclass classes have also had their parent @Entity registered,
         // which Objectify nominally requires but doesn't enforce in 4.x (though it may in 5.x).
@@ -165,10 +168,16 @@ public class ObjectifyService {
       }
       com.googlecode.objectify.ObjectifyService.register(clazz);
       // Autogenerated ids make the commit log code very difficult since we won't always be able
-      // to create a key for an entity immediately when requesting a save. Disallow that here.
-      checkState(
-          !factory().getMetadata(clazz).getKeyMetadata().isIdGeneratable(),
-          "Can't register %s: Autogenerated ids (@Id on a Long) are not supported.", kind);
+      // to create a key for an entity immediately when requesting a save. So, we require such
+      // entities to implement google.registry.model.Buildable as its build() function allocates the
+      // id to the entity.
+      if (factory().getMetadata(clazz).getKeyMetadata().isIdGeneratable()) {
+        checkState(
+            Buildable.class.isAssignableFrom(clazz),
+            "Can't register %s: Entity with autogenerated ids (@Id on a Long) must implement"
+                + " google.registry.model.Buildable.",
+            kind);
+      }
     }
   }
 

core/src/main/java/google/registry/model/poll/PollMessage.java

@@ -62,7 +62,7 @@ import org.joda.time.DateTime;
  * <p>Poll messages are identified externally by registrars using the format defined in {@link
  * PollMessageExternalKeyConverter}.
  *
- * @see <a href="https://tools.ietf.org/html/rfc5730#section-2.9.2.3">RFC5730 - EPP - &ltpoll&gt
+ * @see <a href="https://tools.ietf.org/html/rfc5730#section-2.9.2.3">RFC5730 - EPP - &lt;poll&gt;
  *     Command</a>
  */
 @Entity

core/src/main/java/google/registry/model/registrar/Registrar.java

@@ -109,7 +109,7 @@ import org.joda.time.DateTime;
           name = "registrar_iana_identifier_idx"),
     })
 public class Registrar extends ImmutableObject
-    implements Buildable, Jsonifiable, DatastoreAndSqlEntity {
+    implements Buildable, DatastoreAndSqlEntity, Jsonifiable {
 
   /** Represents the type of a registrar entity. */
   public enum Type {

core/src/main/java/google/registry/model/registrar/RegistrarContact.java

@@ -42,6 +42,7 @@ import google.registry.model.ImmutableObject;
 import google.registry.model.JsonMapBuilder;
 import google.registry.model.Jsonifiable;
 import google.registry.model.annotations.ReportedOn;
+import google.registry.schema.replay.DatastoreAndSqlEntity;
 import java.util.Arrays;
 import java.util.Map;
 import java.util.Optional;
@@ -68,7 +69,8 @@ import javax.persistence.Transient;
       @javax.persistence.Index(columnList = "gaeUserId", name = "registrarpoc_gae_user_id_idx")
     })
 // TODO(shicong): Rename the class name to RegistrarPoc after database migration
-public class RegistrarContact extends ImmutableObject implements Jsonifiable {
+public class RegistrarContact extends ImmutableObject
+    implements DatastoreAndSqlEntity, Jsonifiable {
 
   @Parent @Transient Key<Registrar> parent;
 

core/src/main/java/google/registry/model/registry/label/PremiumList.java

@@ -31,6 +31,7 @@ import com.google.common.cache.CacheBuilder;
 import com.google.common.cache.CacheLoader;
 import com.google.common.cache.CacheLoader.InvalidCacheLoadException;
 import com.google.common.cache.LoadingCache;
+import com.google.common.collect.ImmutableList;
 import com.google.common.hash.BloomFilter;
 import com.google.common.util.concurrent.UncheckedExecutionException;
 import com.googlecode.objectify.Key;
@@ -41,6 +42,8 @@ import google.registry.model.Buildable;
 import google.registry.model.ImmutableObject;
 import google.registry.model.annotations.ReportedOn;
 import google.registry.model.registry.Registry;
+import google.registry.schema.replay.DatastoreEntity;
+import google.registry.schema.replay.SqlEntity;
 import google.registry.util.NonFinalForTesting;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
@@ -53,26 +56,28 @@ import javax.annotation.Nullable;
 import org.joda.money.Money;
 import org.joda.time.Duration;
 
-/**
- * A premium list entity, persisted to Datastore, that is used to check domain label prices.
- */
+/** A premium list entity, persisted to Datastore, that is used to check domain label prices. */
 @ReportedOn
 @Entity
-public final class PremiumList extends BaseDomainLabelList<Money, PremiumList.PremiumListEntry> {
+public final class PremiumList extends BaseDomainLabelList<Money, PremiumList.PremiumListEntry>
+    implements DatastoreEntity {
 
   /** Stores the revision key for the set of currently used premium list entry entities. */
   Key<PremiumListRevision> revisionKey;
 
+  @Override
+  public ImmutableList<SqlEntity> toSqlEntities() {
+    return ImmutableList.of(); // PremiumList is dual-written
+  }
+
   /** Virtual parent entity for premium list entry entities associated with a single revision. */
   @ReportedOn
   @Entity
   public static class PremiumListRevision extends ImmutableObject {
 
-    @Parent
-    Key<PremiumList> parent;
+    @Parent Key<PremiumList> parent;
 
-    @Id
-    long revisionId;
+    @Id long revisionId;
 
     /**
      * A Bloom filter that is used to determine efficiently and quickly whether a label might be
@@ -249,7 +254,7 @@ public final class PremiumList extends BaseDomainLabelList<Money, PremiumList.Pr
   @ReportedOn
   @Entity
   public static class PremiumListEntry extends DomainLabelEntry<Money, PremiumListEntry>
-      implements Buildable {
+      implements Buildable, DatastoreEntity {
 
     @Parent
     Key<PremiumListRevision> parent;
@@ -266,6 +271,11 @@ public final class PremiumList extends BaseDomainLabelList<Money, PremiumList.Pr
       return new Builder(clone(this));
     }
 
+    @Override
+    public ImmutableList<SqlEntity> toSqlEntities() {
+      return null;
+    }
+
     /** A builder for constructing {@link PremiumListEntry} objects, since they are immutable. */
     public static class Builder extends DomainLabelEntry.Builder<PremiumListEntry, Builder> {
 

core/src/main/java/google/registry/model/registry/label/ReservedList.java

@@ -30,6 +30,7 @@ import com.google.common.base.Splitter;
 import com.google.common.cache.CacheBuilder;
 import com.google.common.cache.CacheLoader;
 import com.google.common.cache.LoadingCache;
+import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.collect.MapDifference;
@@ -45,6 +46,8 @@ import com.googlecode.objectify.mapper.Mapper;
 import google.registry.model.Buildable;
 import google.registry.model.registry.Registry;
 import google.registry.model.registry.label.DomainLabelMetrics.MetricsReservedListMatch;
+import google.registry.schema.replay.DatastoreEntity;
+import google.registry.schema.replay.SqlEntity;
 import google.registry.schema.tld.ReservedList.ReservedEntry;
 import google.registry.schema.tld.ReservedListDao;
 import java.util.List;
@@ -59,7 +62,8 @@ import org.joda.time.DateTime;
  */
 @Entity
 public final class ReservedList
-    extends BaseDomainLabelList<ReservationType, ReservedList.ReservedListEntry> {
+    extends BaseDomainLabelList<ReservationType, ReservedList.ReservedListEntry> implements
+    DatastoreEntity {
 
   private static final FluentLogger logger = FluentLogger.forEnclosingClass();
 
@@ -68,6 +72,11 @@ public final class ReservedList
 
   boolean shouldPublish = true;
 
+  @Override
+  public ImmutableList<SqlEntity> toSqlEntities() {
+    return ImmutableList.of(); // ReservedList is dual-written
+  }
+
   /**
    * A reserved list entry entity, persisted to Datastore, that represents a single label and its
    * reservation type.
@@ -149,8 +158,8 @@ public final class ReservedList
   /**
    * Gets a ReservedList by name using the caching layer.
    *
-   * @return An Optional<ReservedList> that has a value if a reserved list exists by the given name,
-   *     or absent if not.
+   * @return An Optional&lt;ReservedList&gt; that has a value if a reserved list exists by the given
+   *     name, or absent if not.
    * @throws UncheckedExecutionException if some other error occurs while trying to load the
    *     ReservedList from the cache or Datastore.
    */

core/src/main/java/google/registry/model/reporting/IcannReportingTypes.java

@@ -22,8 +22,8 @@ public final class IcannReportingTypes {
    * Represents the set of possible ICANN Monthly Registry Functions Activity Report fields.
    *
    * <p>Refer to the <a
-   * href="https://newgtlds.icann.org/sites/default/files/agreements/agreement-approved-09jan14-en.htm#_DV_M278>ICANN
-   * registry agreement Specification 3 Section 2</a> for details.
+   * href="https://newgtlds.icann.org/sites/default/files/agreements/agreement-approved-09jan14-en.htm#_DV_M278">
+   * ICANN registry agreement Specification 3 Section 2</a> for details.
    */
   public enum ActivityReportField {
     DOMAIN_CHECK("srs-dom-check"),

core/src/main/java/google/registry/model/server/Lock.java

@@ -16,20 +16,21 @@ package google.registry.model.server;
 
 import static com.google.common.base.Preconditions.checkArgument;
 import static google.registry.model.ofy.ObjectifyService.ofy;
-import static google.registry.persistence.transaction.TransactionManagerFactory.jpaTm;
 import static google.registry.persistence.transaction.TransactionManagerFactory.tm;
 import static google.registry.util.DateTimeUtils.isAtOrAfter;
 
 import com.google.auto.value.AutoValue;
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Strings;
+import com.google.common.collect.ImmutableList;
 import com.google.common.flogger.FluentLogger;
 import com.googlecode.objectify.annotation.Entity;
 import com.googlecode.objectify.annotation.Id;
 import google.registry.model.ImmutableObject;
 import google.registry.model.annotations.NotBackedUp;
 import google.registry.model.annotations.NotBackedUp.Reason;
-import google.registry.schema.server.LockDao;
+import google.registry.schema.replay.DatastoreEntity;
+import google.registry.schema.replay.SqlEntity;
 import google.registry.util.RequestStatusChecker;
 import google.registry.util.RequestStatusCheckerImpl;
 import java.io.Serializable;
@@ -49,7 +50,7 @@ import org.joda.time.Duration;
  */
 @Entity
 @NotBackedUp(reason = Reason.TRANSIENT)
-public class Lock extends ImmutableObject implements Serializable {
+public class Lock extends ImmutableObject implements DatastoreEntity, Serializable {
 
   private static final long serialVersionUID = 756397280691684645L;
   private static final FluentLogger logger = FluentLogger.forEnclosingClass();
@@ -197,22 +198,6 @@ public class Lock extends ImmutableObject implements Serializable {
 
                   // Checking if an unexpired lock still exists - if so, the lock can't be acquired.
                   Lock lock = ofy().load().type(Lock.class).id(lockId).now();
-                  try {
-                    jpaTm()
-                        .transact(
-                            () -> {
-                              Optional<google.registry.schema.server.Lock> cloudSqlLockOptional;
-                              if (tld == null) {
-                                cloudSqlLockOptional = LockDao.load(resourceName);
-                              } else {
-                                cloudSqlLockOptional = LockDao.load(resourceName, tld);
-                              }
-                              LockDao.compare(Optional.ofNullable(lock), cloudSqlLockOptional);
-                            });
-                  } catch (Exception e) {
-                    logger.atSevere().withCause(e).log(
-                        "Issue loading and comparing lock from Cloud SQL");
-                  }
                   if (lock != null) {
                     logger.atInfo().log(
                         "Loaded existing lock: %s for request: %s", lock.lockId, lock.requestLogId);
@@ -237,35 +222,6 @@ public class Lock extends ImmutableObject implements Serializable {
                   // don't need to be backed up.
                   ofy().saveWithoutBackup().entity(newLock);
 
-                  // create and save the lock to Cloud SQL
-                  try {
-                    jpaTm()
-                        .transact(
-                            () -> {
-                              google.registry.schema.server.Lock cloudSqlLock;
-                              if (tld == null) {
-                                cloudSqlLock =
-                                    google.registry.schema.server.Lock.createGlobal(
-                                        resourceName,
-                                        requestStatusChecker.getLogId(),
-                                        now,
-                                        leaseLength);
-                              } else {
-                                cloudSqlLock =
-                                    google.registry.schema.server.Lock.create(
-                                        resourceName,
-                                        tld,
-                                        requestStatusChecker.getLogId(),
-                                        now,
-                                        leaseLength);
-                              }
-                              LockDao.save(cloudSqlLock);
-                            });
-                  } catch (Exception e) {
-                    logger.atSevere().withCause(e).log(
-                        "Error saving lock to Cloud SQL: %s", newLock);
-                  }
-
                   return AcquireResult.create(now, lock, newLock, lockState);
                 });
 
@@ -284,44 +240,12 @@ public class Lock extends ImmutableObject implements Serializable {
               // this can happen if release() is called around the expiration time and the lock
               // expires underneath us.
               Lock loadedLock = ofy().load().type(Lock.class).id(lockId).now();
-              try {
-                jpaTm()
-                    .transact(
-                        () -> {
-                          Optional<google.registry.schema.server.Lock> cloudSqlLockOptional;
-                          if (tld == null) {
-                            cloudSqlLockOptional = LockDao.load(resourceName);
-                          } else {
-                            cloudSqlLockOptional = LockDao.load(resourceName, tld);
-                          }
-                          LockDao.compare(Optional.ofNullable(loadedLock), cloudSqlLockOptional);
-                        });
-              } catch (Exception e) {
-                logger.atSevere().withCause(e).log(
-                    "Issue loading and comparing lock from Cloud SQL");
-              }
               if (Lock.this.equals(loadedLock)) {
                 // Use noBackupOfy() so that we don't create a commit log entry for deleting the
                 // lock.
                 logger.atInfo().log("Deleting lock: %s", lockId);
                 ofy().deleteWithoutBackup().entity(Lock.this);
 
-                // Remove the lock from Cloud SQL
-                try {
-                  jpaTm()
-                      .transact(
-                          () -> {
-                            if (tld == null) {
-                              LockDao.delete(resourceName);
-                            } else {
-                              LockDao.delete(resourceName, tld);
-                            }
-                          });
-                } catch (Exception e) {
-                  logger.atSevere().withCause(e).log(
-                      "Error deleting lock from Cloud SQL: %s", loadedLock);
-                }
-
                 lockMetrics.recordRelease(
                     resourceName, tld, new Duration(acquiredTime, tm().getTransactionTime()));
               } else {
@@ -335,4 +259,9 @@ public class Lock extends ImmutableObject implements Serializable {
               }
             });
   }
+
+  @Override
+  public ImmutableList<SqlEntity> toSqlEntities() {
+    return ImmutableList.of(); // Locks are not converted since they are ephemeral
+  }
 }

core/src/main/java/google/registry/model/tmch/ClaimsListShard.java

@@ -26,6 +26,7 @@ import static google.registry.util.DateTimeUtils.START_OF_TIME;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Supplier;
+import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.common.collect.MapDifference;
 import com.google.common.collect.MapDifference.ValueDifference;
@@ -44,6 +45,8 @@ import google.registry.model.annotations.NotBackedUp;
 import google.registry.model.annotations.NotBackedUp.Reason;
 import google.registry.model.annotations.VirtualEntity;
 import google.registry.model.common.CrossTldSingleton;
+import google.registry.schema.replay.DatastoreEntity;
+import google.registry.schema.replay.SqlEntity;
 import google.registry.schema.tmch.ClaimsList;
 import google.registry.schema.tmch.ClaimsListDao;
 import google.registry.util.CollectionUtils;
@@ -75,7 +78,7 @@ import org.joda.time.DateTime;
  */
 @Entity
 @NotBackedUp(reason = Reason.EXTERNALLY_SOURCED)
-public class ClaimsListShard extends ImmutableObject {
+public class ClaimsListShard extends ImmutableObject implements DatastoreEntity {
 
   private static final FluentLogger logger = FluentLogger.forEnclosingClass();
 
@@ -289,10 +292,15 @@ public class ClaimsListShard extends ImmutableObject {
     }
   }
 
+  @Override
+  public ImmutableList<SqlEntity> toSqlEntities() {
+    return ImmutableList.of(); // ClaimsLists are dually written
+  }
+
   /** Virtual parent entity for claims list shards of a specific revision. */
   @Entity
   @VirtualEntity
-  public static class ClaimsListRevision extends ImmutableObject {
+  public static class ClaimsListRevision extends ImmutableObject implements DatastoreEntity {
     @Parent
     Key<ClaimsListSingleton> parent;
 
@@ -311,6 +319,11 @@ public class ClaimsListShard extends ImmutableObject {
     public static Key<ClaimsListRevision> createKey() {
       return createKey(new ClaimsListSingleton());
     }
+
+    @Override
+    public ImmutableList<SqlEntity> toSqlEntities() {
+      return ImmutableList.of(); // ClaimsLists are dually written
+    }
   }
 
   /**
@@ -319,7 +332,7 @@ public class ClaimsListShard extends ImmutableObject {
    */
   @Entity
   @NotBackedUp(reason = Reason.EXTERNALLY_SOURCED)
-  public static class ClaimsListSingleton extends CrossTldSingleton {
+  public static class ClaimsListSingleton extends CrossTldSingleton implements DatastoreEntity {
     Key<ClaimsListRevision> activeRevision;
 
     static ClaimsListSingleton create(Key<ClaimsListRevision> revision) {
@@ -332,6 +345,11 @@ public class ClaimsListShard extends ImmutableObject {
     public void setActiveRevision(Key<ClaimsListRevision> revision) {
       activeRevision = revision;
     }
+
+    @Override
+    public ImmutableList<SqlEntity> toSqlEntities() {
+      return ImmutableList.of(); // ClaimsLists are dually written
+    }
   }
 
   /**

core/src/main/java/google/registry/model/translators/VKeyTranslatorFactory.java

@@ -14,13 +14,14 @@
 
 package google.registry.model.translators;
 
-import static java.nio.charset.StandardCharsets.UTF_8;
+import static com.google.common.base.Functions.identity;
+import static com.google.common.collect.ImmutableMap.toImmutableMap;
+import static google.registry.model.EntityClasses.ALL_CLASSES;
 
-import com.googlecode.objectify.Key;
+import com.google.appengine.api.datastore.Key;
+import com.google.common.collect.ImmutableMap;
+import com.googlecode.objectify.annotation.EntitySubclass;
 import google.registry.persistence.VKey;
-import java.io.UnsupportedEncodingException;
-import java.net.URLDecoder;
-import java.net.URLEncoder;
 
 /**
  * Translator factory for VKey.
@@ -28,57 +29,39 @@ import java.net.URLEncoder;
  * <p>These get translated to a string containing the URL safe encoding of the objectify key
  * followed by a (url-unsafe) ampersand delimiter and the SQL key.
  */
-public class VKeyTranslatorFactory<T> extends AbstractSimpleTranslatorFactory<VKey, String> {
-  private final Class<T> refClass;
+public class VKeyTranslatorFactory extends AbstractSimpleTranslatorFactory<VKey, Key> {
 
-  public VKeyTranslatorFactory(Class<T> refClass) {
+  // Class registry allowing us to restore the original class object from the unqualified class
+  // name, which is all the datastore key gives us.
+  // Note that entities annotated with @EntitySubclass are removed because they share the same
+  // kind of the key with their parent class.
+  private static final ImmutableMap<String, Class> CLASS_REGISTRY =
+      ALL_CLASSES.stream()
+          .filter(clazz -> !clazz.isAnnotationPresent(EntitySubclass.class))
+          .collect(toImmutableMap(com.googlecode.objectify.Key::getKind, identity()));
+  ;
+
+  public VKeyTranslatorFactory() {
     super(VKey.class);
-    this.refClass = refClass;
   }
 
   @Override
-  public SimpleTranslator<VKey, String> createTranslator() {
-    return new SimpleTranslator<VKey, String>() {
+  public SimpleTranslator<VKey, Key> createTranslator() {
+    return new SimpleTranslator<VKey, Key>() {
       @Override
-      public VKey loadValue(String datastoreValue) {
-        int pos = datastoreValue.indexOf('&');
-        Key ofyKey = null;
-        String sqlKey = null;
-        if (pos > 0) {
-          // We have an objectify key.
-          ofyKey = Key.create(datastoreValue.substring(0, pos));
-        }
-
-        if (pos < datastoreValue.length() - 1) {
-          // We have an SQL key.
-          sqlKey = decode(datastoreValue.substring(pos + 1));
-        }
-
-        return VKey.create(refClass, sqlKey, ofyKey);
+      public VKey loadValue(Key datastoreValue) {
+        // TODO(mmuller): we need to call a method on refClass to also reconstitute the SQL key.
+        return datastoreValue == null
+            ? null
+            : VKey.createOfy(
+                CLASS_REGISTRY.get(datastoreValue.getKind()),
+                com.googlecode.objectify.Key.create(datastoreValue));
       }
 
       @Override
-      public String saveValue(VKey key) {
-        return ((key.getOfyKey() == null) ? "" : key.getOfyKey().getString())
-            + "&"
-            + ((key.getSqlKey() == null) ? "" : encode(key.getSqlKey().toString()));
+      public Key saveValue(VKey key) {
+        return key == null ? null : key.getOfyKey().getRaw();
       }
     };
   }
-
-  private static String encode(String val) {
-    try {
-      return URLEncoder.encode(val, UTF_8.toString());
-    } catch (UnsupportedEncodingException e) {
-      throw new RuntimeException(e);
-    }
-  }
-
-  private static String decode(String encoded) {
-    try {
-      return URLDecoder.decode(encoded, UTF_8.toString());
-    } catch (UnsupportedEncodingException e) {
-      throw new RuntimeException(e);
-    }
-  }
 }

core/src/main/java/google/registry/persistence/PersistenceModule.java

@@ -17,7 +17,9 @@ package google.registry.persistence;
 import static com.google.common.base.Preconditions.checkState;
 import static google.registry.config.RegistryConfig.getHibernateConnectionIsolation;
 import static google.registry.config.RegistryConfig.getHibernateHikariConnectionTimeout;
+import static google.registry.config.RegistryConfig.getHibernateHikariIdleTimeout;
 import static google.registry.config.RegistryConfig.getHibernateHikariMaximumPoolSize;
+import static google.registry.config.RegistryConfig.getHibernateHikariMinimumIdle;
 import static google.registry.config.RegistryConfig.getHibernateLogSqlQueries;
 
 import com.google.api.client.auth.oauth2.Credential;
@@ -48,7 +50,10 @@ public class PersistenceModule {
   // This name must be the same as the one defined in persistence.xml.
   public static final String PERSISTENCE_UNIT_NAME = "nomulus";
   public static final String HIKARI_CONNECTION_TIMEOUT = "hibernate.hikari.connectionTimeout";
+  public static final String HIKARI_MINIMUM_IDLE = "hibernate.hikari.minimumIdle";
   public static final String HIKARI_MAXIMUM_POOL_SIZE = "hibernate.hikari.maximumPoolSize";
+  public static final String HIKARI_IDLE_TIMEOUT = "hibernate.hikari.idleTimeout";
+
   public static final String HIKARI_DS_SOCKET_FACTORY = "hibernate.hikari.dataSource.socketFactory";
   public static final String HIKARI_DS_CLOUD_SQL_INSTANCE =
       "hibernate.hikari.dataSource.cloudSqlInstance";
@@ -74,7 +79,9 @@ public class PersistenceModule {
     properties.put(Environment.ISOLATION, getHibernateConnectionIsolation());
     properties.put(Environment.SHOW_SQL, getHibernateLogSqlQueries());
     properties.put(HIKARI_CONNECTION_TIMEOUT, getHibernateHikariConnectionTimeout());
+    properties.put(HIKARI_MINIMUM_IDLE, getHibernateHikariMinimumIdle());
     properties.put(HIKARI_MAXIMUM_POOL_SIZE, getHibernateHikariMaximumPoolSize());
+    properties.put(HIKARI_IDLE_TIMEOUT, getHibernateHikariIdleTimeout());
     properties.put(Environment.DIALECT, NomulusPostgreSQLDialect.class.getName());
     return properties.build();
   }

core/src/main/java/google/registry/persistence/VKey.java

@@ -15,6 +15,7 @@
 package google.registry.persistence;
 
 import static com.google.common.base.Preconditions.checkState;
+import static google.registry.util.PreconditionsUtils.checkArgumentNotNull;
 
 import google.registry.model.ImmutableObject;
 import java.util.Optional;
@@ -41,20 +42,31 @@ public class VKey<T> extends ImmutableObject {
     this.primaryKey = primaryKey;
   }
 
-  public static <T> VKey<T> createSql(Class<? extends T> kind, Object primaryKey) {
-    return new VKey(kind, null, primaryKey);
+  /** Creates a {@link VKey} which only contains the sql primary key. */
+  public static <T> VKey<T> createSql(Class<? extends T> kind, Object sqlKey) {
+    checkArgumentNotNull(kind, "kind must not be null");
+    checkArgumentNotNull(sqlKey, "sqlKey must not be null");
+    return new VKey(kind, null, sqlKey);
   }
 
+  /** Creates a {@link VKey} which only contains the ofy primary key. */
   public static <T> VKey<T> createOfy(
-      Class<? extends T> kind, com.googlecode.objectify.Key<T> ofyKey) {
+      Class<? extends T> kind, com.googlecode.objectify.Key<? extends T> ofyKey) {
+    checkArgumentNotNull(kind, "kind must not be null");
+    checkArgumentNotNull(ofyKey, "ofyKey must not be null");
     return new VKey(kind, ofyKey, null);
   }
 
+  /** Creates a {@link VKey} which only contains both sql and ofy primary key. */
   public static <T> VKey<T> create(
-      Class<? extends T> kind, Object primaryKey, com.googlecode.objectify.Key ofyKey) {
-    return new VKey(kind, ofyKey, primaryKey);
+      Class<? extends T> kind, Object sqlKey, com.googlecode.objectify.Key ofyKey) {
+    checkArgumentNotNull(kind, "kind must not be null");
+    checkArgumentNotNull(sqlKey, "sqlKey must not be null");
+    checkArgumentNotNull(ofyKey, "ofyKey must not be null");
+    return new VKey(kind, ofyKey, sqlKey);
   }
 
+  /** Returns the type of the entity. */
   public Class<? extends T> getKind() {
     return this.kind;
   }

core/src/main/java/google/registry/persistence/WithLongVKey.java

@@ -0,0 +1,34 @@
+// Copyright 2020 The Nomulus Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package google.registry.persistence;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Target;
+import javax.persistence.AttributeConverter;
+import javax.persistence.Entity;
+
+/**
+ * Annotation for {@link Entity} which id is long type and needs an {@link AttributeConverter} for
+ * its VKey.
+ */
+@Target({ElementType.TYPE})
+public @interface WithLongVKey {
+  /**
+   * Sets the suffix of the class name for the {@link AttributeConverter} generated by
+   * LongVKeyProcessor. If not set, the suffix will be the type name of the VKey. Note that the
+   * class name will be "VKeyConverter_" concatenated with the suffix.
+   */
+  String classNameSuffix() default "";
+}

core/src/main/java/google/registry/persistence/WithStringVKey.java

@@ -0,0 +1,34 @@
+// Copyright 2020 The Nomulus Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package google.registry.persistence;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Target;
+import javax.persistence.AttributeConverter;
+import javax.persistence.Entity;
+
+/**
+ * Annotation for {@link Entity} which id is string type and needs an {@link AttributeConverter} for
+ * its VKey.
+ */
+@Target({ElementType.TYPE})
+public @interface WithStringVKey {
+  /**
+   * Sets the suffix of the class name for the {@link AttributeConverter} generated by
+   * StringVKeyProcessor. If not set, the suffix will be the type name of the VKey. Note that the
+   * class name will be "VKeyConverter_" concatenated with the suffix.
+   */
+  String classNameSuffix() default "";
+}

core/src/main/java/google/registry/persistence/converter/BillingCostTransitionConverter.java

@@ -0,0 +1,47 @@
+// Copyright 2020 The Nomulus Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package google.registry.persistence.converter;
+
+import avro.shaded.com.google.common.collect.Maps;
+import google.registry.model.registry.Registry.BillingCostTransition;
+import java.util.Map;
+import javax.persistence.Converter;
+import org.joda.money.Money;
+import org.joda.time.DateTime;
+
+/**
+ * JPA converter for storing/retrieving {@code TimedTransitionProperty<Money,BillingCostTransition>}
+ * objects.
+ */
+@Converter(autoApply = true)
+public class BillingCostTransitionConverter
+    extends TimedTransitionPropertyConverterBase<Money, BillingCostTransition> {
+
+  @Override
+  Map.Entry<String, String> convertToDatabaseMapEntry(
+      Map.Entry<DateTime, BillingCostTransition> entry) {
+    return Maps.immutableEntry(entry.getKey().toString(), entry.getValue().getValue().toString());
+  }
+
+  @Override
+  Map.Entry<DateTime, Money> convertToEntityMapEntry(Map.Entry<String, String> entry) {
+    return Maps.immutableEntry(DateTime.parse(entry.getKey()), Money.parse(entry.getValue()));
+  }
+
+  @Override
+  Class<BillingCostTransition> getTimedTransitionSubclass() {
+    return BillingCostTransition.class;
+  }
+}

core/src/main/java/google/registry/persistence/converter/BillingEventFlagSetConverter.java

@@ -0,0 +1,35 @@
+// Copyright 2020 The Nomulus Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package google.registry.persistence.converter;
+
+import google.registry.model.billing.BillingEvent.Flag;
+import java.util.Set;
+import javax.persistence.AttributeConverter;
+import javax.persistence.Converter;
+
+/** JPA {@link AttributeConverter} for storing/retrieving {@link Set}. */
+@Converter(autoApply = true)
+public class BillingEventFlagSetConverter extends StringSetConverterBase<Flag> {
+
+  @Override
+  String toString(Flag element) {
+    return element.name();
+  }
+
+  @Override
+  Flag fromString(String value) {
+    return Flag.valueOf(value);
+  }
+}

core/src/main/java/google/registry/persistence/converter/CidrAddressBlockListConverter.java

@@ -15,12 +15,11 @@
 package google.registry.persistence.converter;
 
 import google.registry.util.CidrAddressBlock;
-import java.util.List;
 import javax.persistence.AttributeConverter;
 import javax.persistence.Converter;
 
 /**
- * JPA {@link AttributeConverter} for storing/retrieving {@link List<CidrAddressBlock>} objects.
+ * JPA {@link AttributeConverter} for storing/retrieving {@code List<CidrAddressBlock>} objects.
  * TODO(shicong): Investigate if we can have one converter for any List type
  */
 @Converter(autoApply = true)

core/src/main/java/google/registry/persistence/converter/CurrencyToBillingConverter.java

@@ -21,7 +21,7 @@ import java.util.Map;
 import javax.persistence.Converter;
 import org.joda.money.CurrencyUnit;
 
-/** JPA converter for storing/retrieving {@link Map <CurrencyUnit, BillingAccountEntry>} objects. */
+/** JPA converter for storing/retrieving {@code Map<CurrencyUnit, BillingAccountEntry>} objects. */
 @Converter(autoApply = true)
 public class CurrencyToBillingConverter
     extends StringMapConverterBase<CurrencyUnit, BillingAccountEntry> {

core/src/main/java/google/registry/persistence/converter/PostalInfoChoiceListConverter.java

@@ -16,11 +16,10 @@ package google.registry.persistence.converter;
 
 import google.registry.model.contact.Disclose.PostalInfoChoice;
 import google.registry.model.contact.PostalInfo;
-import java.util.List;
 import javax.persistence.AttributeConverter;
 import javax.persistence.Converter;
 
-/** JPA {@link AttributeConverter} for storing/retrieving {@link List < PostalInfoChoice >}. */
+/** JPA {@link AttributeConverter} for storing/retrieving {@code List<PostalInfoChoice>}. */
 @Converter(autoApply = true)
 public class PostalInfoChoiceListConverter extends StringListConverterBase<PostalInfoChoice> {
 

core/src/main/java/google/registry/persistence/converter/RegistrarPocSetConverter.java

@@ -15,11 +15,10 @@
 package google.registry.persistence.converter;
 
 import google.registry.model.registrar.RegistrarContact.Type;
-import java.util.Set;
 import javax.persistence.AttributeConverter;
 import javax.persistence.Converter;
 
-/** JPA {@link AttributeConverter} for storing/retrieving {@link Set<Type>}. */
+/** JPA {@link AttributeConverter} for storing/retrieving {@code Set<Type>}. */
 @Converter(autoApply = true)
 public class RegistrarPocSetConverter extends StringSetConverterBase<Type> {
   @Override

core/src/main/java/google/registry/persistence/converter/StatusValueSetConverter.java

@@ -15,11 +15,10 @@
 package google.registry.persistence.converter;
 
 import google.registry.model.eppcommon.StatusValue;
-import java.util.Set;
 import javax.persistence.AttributeConverter;
 import javax.persistence.Converter;
 
-/** JPA {@link AttributeConverter} for storing/retrieving {@link Set<StatusValue>}. */
+/** JPA {@link AttributeConverter} for storing/retrieving {@code Set<StatusValue>}. */
 @Converter(autoApply = true)
 public class StatusValueSetConverter extends StringSetConverterBase<StatusValue> {
 

core/src/main/java/google/registry/persistence/converter/StringCollectionDescriptor.java

@@ -37,7 +37,7 @@ import org.hibernate.type.descriptor.sql.SqlTypeDescriptor;
 /**
  * The {@link JavaTypeDescriptor} and {@link SqlTypeDescriptor} for {@link StringCollection}.
  *
- * <p>A {@link StringCollection} object is a simple wrapper for a {@link Collection<String>} which
+ * <p>A {@link StringCollection} object is a simple wrapper for a {@code Collection<String>} which
  * can be stored as a string array in the database. The {@link JavaTypeDescriptor} and {@link
  * SqlTypeDescriptor} is used by JPA/Hibernate to map between the collection and {@link Array} which
  * is the actual type that JDBC uses to read from and write to the database.

core/src/main/java/google/registry/persistence/converter/StringListConverter.java

@@ -14,11 +14,10 @@
 
 package google.registry.persistence.converter;
 
-import java.util.List;
 import javax.persistence.AttributeConverter;
 import javax.persistence.Converter;
 
-/** JPA {@link AttributeConverter} for storing/retrieving {@link List<String>}. */
+/** JPA {@link AttributeConverter} for storing/retrieving {@code List<String>}. */
 @Converter(autoApply = true)
 public class StringListConverter extends StringListConverterBase<String> {
 

core/src/main/java/google/registry/persistence/converter/StringMapDescriptor.java

@@ -36,7 +36,7 @@ import org.hibernate.type.descriptor.sql.SqlTypeDescriptor;
 /**
  * The {@link JavaTypeDescriptor} and {@link SqlTypeDescriptor} for {@link StringMap}.
  *
- * <p>A {@link StringMap} object is a simple wrapper for a {@link Map <String, String>} which can be
+ * <p>A {@link StringMap} object is a simple wrapper for a {@code Map<String, String>} which can be
  * stored in a column with data type of hstore in the database. The {@link JavaTypeDescriptor} and
  * {@link SqlTypeDescriptor} is used by JPA/Hibernate to map between the map and hstore which is the
  * actual type that JDBC uses to read from and write to the database.
@@ -156,7 +156,7 @@ public class StringMapDescriptor extends AbstractTypeDescriptor<StringMap>
     };
   }
 
-  /** A simple wrapper class for {@link Map<String, String>}. */
+  /** A simple wrapper class for {@code Map<String, String>}. */
   public static class StringMap {
     private Map<String, String> map;
 
@@ -169,7 +169,7 @@ public class StringMapDescriptor extends AbstractTypeDescriptor<StringMap>
       return new StringMap(ImmutableMap.copyOf(map));
     }
 
-    /** Returns the underlying {@link Map<String, String>} object. */
+    /** Returns the underlying {@code Map<String, String>} object. */
     public Map<String, String> getMap() {
       return map;
     }

core/src/main/java/google/registry/persistence/converter/StringSetConverter.java

@@ -14,11 +14,10 @@
 
 package google.registry.persistence.converter;
 
-import java.util.Set;
 import javax.persistence.AttributeConverter;
 import javax.persistence.Converter;
 
-/** JPA {@link AttributeConverter} for storing/retrieving {@link Set<String>}. */
+/** JPA {@link AttributeConverter} for storing/retrieving {@code Set<String>}. */
 @Converter(autoApply = true)
 public class StringSetConverter extends StringSetConverterBase<String> {
 

core/src/main/java/google/registry/persistence/converter/TimedTransitionPropertyConverterBase.java

@@ -0,0 +1,63 @@
+// Copyright 2020 The Nomulus Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package google.registry.persistence.converter;
+
+import static com.google.common.collect.ImmutableMap.toImmutableMap;
+
+import com.google.common.collect.ImmutableSortedMap;
+import google.registry.model.common.TimedTransitionProperty;
+import google.registry.model.common.TimedTransitionProperty.TimedTransition;
+import google.registry.persistence.converter.StringMapDescriptor.StringMap;
+import java.util.Map;
+import javax.annotation.Nullable;
+import javax.persistence.AttributeConverter;
+import org.joda.time.DateTime;
+
+/**
+ * Base JPA converter for {@link TimedTransitionProperty} objects that are stored in a column with
+ * data type of hstore in the database.
+ */
+public abstract class TimedTransitionPropertyConverterBase<K, V extends TimedTransition<K>>
+    implements AttributeConverter<TimedTransitionProperty<K, V>, StringMap> {
+
+  abstract Map.Entry<String, String> convertToDatabaseMapEntry(Map.Entry<DateTime, V> entry);
+
+  abstract Map.Entry<DateTime, K> convertToEntityMapEntry(Map.Entry<String, String> entry);
+
+  abstract Class<V> getTimedTransitionSubclass();
+
+  @Override
+  public StringMap convertToDatabaseColumn(@Nullable TimedTransitionProperty<K, V> attribute) {
+    return attribute == null
+        ? null
+        : StringMap.create(
+            attribute.entrySet().stream()
+                .map(this::convertToDatabaseMapEntry)
+                .collect(toImmutableMap(Map.Entry::getKey, Map.Entry::getValue)));
+  }
+
+  @Override
+  public TimedTransitionProperty<K, V> convertToEntityAttribute(@Nullable StringMap dbData) {
+    if (dbData == null) {
+      return null;
+    }
+    Map<DateTime, K> map =
+        dbData.getMap().entrySet().stream()
+            .map(this::convertToEntityMapEntry)
+            .collect(toImmutableMap(Map.Entry::getKey, Map.Entry::getValue));
+    return TimedTransitionProperty.fromValueMap(
+        ImmutableSortedMap.copyOf(map), getTimedTransitionSubclass());
+  }
+}

core/src/main/java/google/registry/persistence/converter/TldStateTransitionConverter.java

@@ -0,0 +1,47 @@
+// Copyright 2020 The Nomulus Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package google.registry.persistence.converter;
+
+import com.google.common.collect.Maps;
+import google.registry.model.registry.Registry.TldState;
+import google.registry.model.registry.Registry.TldStateTransition;
+import java.util.Map;
+import javax.persistence.Converter;
+import org.joda.time.DateTime;
+
+/**
+ * JPA converter for storing/retrieving {@code TimedTransitionProperty<TldState,
+ * TldStateTransition>} objects.
+ */
+@Converter(autoApply = true)
+public class TldStateTransitionConverter
+    extends TimedTransitionPropertyConverterBase<TldState, TldStateTransition> {
+
+  @Override
+  Map.Entry<String, String> convertToDatabaseMapEntry(
+      Map.Entry<DateTime, TldStateTransition> entry) {
+    return Maps.immutableEntry(entry.getKey().toString(), entry.getValue().getValue().name());
+  }
+
+  @Override
+  Map.Entry<DateTime, TldState> convertToEntityMapEntry(Map.Entry<String, String> entry) {
+    return Maps.immutableEntry(DateTime.parse(entry.getKey()), TldState.valueOf(entry.getValue()));
+  }
+
+  @Override
+  Class<TldStateTransition> getTimedTransitionSubclass() {
+    return TldStateTransition.class;
+  }
+}

core/src/main/java/google/registry/persistence/converter/VKeyConverter.java

@@ -19,16 +19,16 @@ import javax.annotation.Nullable;
 import javax.persistence.AttributeConverter;
 
 /** Converts VKey to a string column. */
-public abstract class VKeyConverter<T> implements AttributeConverter<VKey<T>, String> {
+public abstract class VKeyConverter<T, C> implements AttributeConverter<VKey<? extends T>, C> {
   @Override
   @Nullable
-  public String convertToDatabaseColumn(@Nullable VKey<T> attribute) {
-    return attribute == null ? null : (String) attribute.getSqlKey();
+  public C convertToDatabaseColumn(@Nullable VKey<? extends T> attribute) {
+    return attribute == null ? null : (C) attribute.getSqlKey();
   }
 
   @Override
   @Nullable
-  public VKey<T> convertToEntityAttribute(@Nullable String dbData) {
+  public VKey<? extends T> convertToEntityAttribute(@Nullable C dbData) {
     return dbData == null ? null : VKey.createSql(getAttributeClass(), dbData);
   }
 

core/src/main/java/google/registry/persistence/transaction/JpaTransactionManager.java

@@ -14,6 +14,7 @@
 
 package google.registry.persistence.transaction;
 
+import google.registry.persistence.VKey;
 import javax.persistence.EntityManager;
 
 /** Sub-interface of {@link TransactionManager} which defines JPA related methods. */
@@ -21,4 +22,7 @@ public interface JpaTransactionManager extends TransactionManager {
 
   /** Returns the {@link EntityManager} for the current request. */
   EntityManager getEntityManager();
+
+  /** Deletes the entity by its id, throws exception if the entity is not deleted. */
+  public abstract <T> void assertDelete(VKey<T> key);
 }

core/src/main/java/google/registry/persistence/transaction/JpaTransactionManagerImpl.java

@@ -77,7 +77,7 @@ public class JpaTransactionManagerImpl implements JpaTransactionManager {
   @Override
   public void assertInTransaction() {
     if (!inTransaction()) {
-      throw new PersistenceException("Not in a transaction");
+      throw new IllegalStateException("Not in a transaction");
     }
   }
 
@@ -232,12 +232,23 @@ public class JpaTransactionManagerImpl implements JpaTransactionManager {
   }
 
   @Override
-  public <T> Optional<T> load(VKey<T> key) {
+  public <T> Optional<T> maybeLoad(VKey<T> key) {
     checkArgumentNotNull(key, "key must be specified");
     assertInTransaction();
     return Optional.ofNullable(getEntityManager().find(key.getKind(), key.getSqlKey()));
   }
 
+  @Override
+  public <T> T load(VKey<T> key) {
+    checkArgumentNotNull(key, "key must be specified");
+    assertInTransaction();
+    T result = getEntityManager().find(key.getKind(), key.getSqlKey());
+    if (result == null) {
+      throw new NoSuchElementException(key.toString());
+    }
+    return result;
+  }
+
   @Override
   public <T> ImmutableList<T> load(Iterable<VKey<T>> keys) {
     checkArgumentNotNull(keys, "keys must be specified");
@@ -267,8 +278,7 @@ public class JpaTransactionManagerImpl implements JpaTransactionManager {
             .getResultList());
   }
 
-  @Override
-  public <T> int delete(VKey<T> key) {
+  private <T> int internalDelete(VKey<T> key) {
     checkArgumentNotNull(key, "key must be specified");
     assertInTransaction();
     EntityType<?> entityType = getEntityType(key.getKind());
@@ -280,9 +290,14 @@ public class JpaTransactionManagerImpl implements JpaTransactionManager {
     return query.executeUpdate();
   }
 
+  @Override
+  public <T> void delete(VKey<T> key) {
+    internalDelete(key);
+  }
+
   @Override
   public <T> void assertDelete(VKey<T> key) {
-    if (delete(key) != 1) {
+    if (internalDelete(key) != 1) {
       throw new IllegalArgumentException(
           String.format("Error deleting the entity of the key: %s", key.getSqlKey()));
     }

core/src/main/java/google/registry/persistence/transaction/TransactionManager.java

@@ -17,6 +17,7 @@ package google.registry.persistence.transaction;
 import com.google.common.collect.ImmutableCollection;
 import com.google.common.collect.ImmutableList;
 import google.registry.persistence.VKey;
+import java.util.NoSuchElementException;
 import java.util.Optional;
 import java.util.function.Supplier;
 import org.joda.time.DateTime;
@@ -108,7 +109,10 @@ public interface TransactionManager {
   <T> boolean checkExists(VKey<T> key);
 
   /** Loads the entity by its id, returns empty if the entity doesn't exist. */
-  <T> Optional<T> load(VKey<T> key);
+  <T> Optional<T> maybeLoad(VKey<T> key);
+
+  /** Loads the entity by its id, throws NoSuchElementException if it doesn't exist. */
+  <T> T load(VKey<T> key);
 
   /**
    * Leads the set of entities by their key id.
@@ -120,9 +124,6 @@ public interface TransactionManager {
   /** Loads all entities of the given type, returns empty if there is no such entity. */
   <T> ImmutableList<T> loadAll(Class<T> clazz);
 
-  /** Deletes the entity by its id, returns the number of deleted entity. */
-  <T> int delete(VKey<T> key);
-
-  /** Deletes the entity by its id, throws exception if the entity is not deleted. */
-  <T> void assertDelete(VKey<T> key);
+  /** Deletes the entity by its id. */
+  <T> void delete(VKey<T> key);
 }

core/src/main/java/google/registry/persistence/transaction/TransactionManagerFactory.java

@@ -16,6 +16,7 @@ package google.registry.persistence.transaction;
 
 import com.google.appengine.api.utils.SystemProperty;
 import com.google.appengine.api.utils.SystemProperty.Environment.Value;
+import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Suppliers;
 import google.registry.model.ofy.DatastoreTransactionManager;
 import google.registry.persistence.DaggerPersistenceComponent;
@@ -26,7 +27,9 @@ import java.util.function.Supplier;
 // TODO: Rename this to PersistenceFactory and move to persistence package.
 public class TransactionManagerFactory {
 
-  private static final TransactionManager TM = createTransactionManager();
+  private static final DatastoreTransactionManager ofyTm = createTransactionManager();
+
+  @NonFinalForTesting private static TransactionManager tm = ofyTm;
 
   /** Supplier for jpaTm so that it is initialized only once, upon first usage. */
   @NonFinalForTesting
@@ -45,10 +48,7 @@ public class TransactionManagerFactory {
     }
   }
 
-  private static TransactionManager createTransactionManager() {
-    // TODO: Determine how to provision TransactionManager after the dual-write. During the
-    // dual-write transitional phase, we need the TransactionManager for both Datastore and Cloud
-    // SQL, and this method returns the one for Datastore.
+  private static DatastoreTransactionManager createTransactionManager() {
     return new DatastoreTransactionManager(null);
   }
 
@@ -67,7 +67,7 @@ public class TransactionManagerFactory {
 
   /** Returns {@link TransactionManager} instance. */
   public static TransactionManager tm() {
-    return TM;
+    return tm;
   }
 
   /** Returns {@link JpaTransactionManager} instance. */
@@ -75,8 +75,20 @@ public class TransactionManagerFactory {
     return jpaTm.get();
   }
 
+  /** Returns {@link DatastoreTransactionManager} instance. */
+  @VisibleForTesting
+  public static DatastoreTransactionManager ofyTm() {
+    return ofyTm;
+  }
+
   /** Sets the return of {@link #jpaTm()} to the given instance of {@link JpaTransactionManager}. */
   public static void setJpaTm(JpaTransactionManager newJpaTm) {
     jpaTm = Suppliers.ofInstance(newJpaTm);
   }
+
+  /** Sets the return of {@link #tm()} to the given instance of {@link TransactionManager}. */
+  @VisibleForTesting
+  public static void setTm(TransactionManager newTm) {
+    tm = newTm;
+  }
 }

core/src/main/java/google/registry/rdap/RdapDomainSearchAction.java

@@ -61,10 +61,9 @@ import javax.inject.Inject;
  *     (RDAP) Query Format</a>
  * @see <a href="http://tools.ietf.org/html/rfc7483">RFC 7483: JSON Responses for the Registration
  *     Data Access Protocol (RDAP)</a>
- *
- * TODO(guyben):This isn't required by the RDAP Technical Implementation Guide, and hence should be
- * deleted, at least until it's actually required.
  */
+// TODO: This isn't required by the RDAP Technical Implementation Guide, and hence should be
+// deleted, at least until it's actually required.
 @Action(
     service = Action.Service.PUBAPI,
     path = "/rdap/domains",

core/src/main/java/google/registry/rdap/RdapEntitySearchAction.java

@@ -72,10 +72,9 @@ import javax.inject.Inject;
  *     (RDAP) Query Format</a>
  * @see <a href="http://tools.ietf.org/html/rfc7483">RFC 7483: JSON Responses for the Registration
  *     Data Access Protocol (RDAP)</a>
- *
- * TODO(guyben):This isn't required by the RDAP Technical Implementation Guide, and hence should be
- * deleted, at least until it's actually required.
  */
+// TODO: This isn't required by the RDAP Technical Implementation Guide, and hence should be
+// deleted, at least until it's actually required.
 @Action(
     service = Action.Service.PUBAPI,
     path = "/rdap/entities",

core/src/main/java/google/registry/rdap/RdapJsonFormatter.java

@@ -52,6 +52,7 @@ import google.registry.model.registrar.Registrar;
 import google.registry.model.registrar.RegistrarAddress;
 import google.registry.model.registrar.RegistrarContact;
 import google.registry.model.reporting.HistoryEntry;
+import google.registry.persistence.VKey;
 import google.registry.rdap.RdapDataStructures.Event;
 import google.registry.rdap.RdapDataStructures.EventAction;
 import google.registry.rdap.RdapDataStructures.Link;
@@ -346,7 +347,12 @@ public class RdapJsonFormatter {
         ImmutableSet.copyOf(tm().load(domainBase.getNameservers()));
     // Load the registrant and other contacts and add them to the data.
     Map<Key<ContactResource>, ContactResource> loadedContacts =
-        ofy().load().keys(domainBase.getReferencedContacts());
+        ofy()
+            .load()
+            .keys(
+                domainBase.getReferencedContacts().stream()
+                    .map(VKey::getOfyKey)
+                    .collect(toImmutableSet()));
     // RDAP Response Profile 2.7.3, A domain MUST have the REGISTRANT, ADMIN, TECH roles and MAY
     // have others. We also add the BILLING.
     //
@@ -361,7 +367,7 @@ public class RdapJsonFormatter {
             .sorted(DESIGNATED_CONTACT_ORDERING)
             .collect(
                 toImmutableSetMultimap(
-                    DesignatedContact::getContactKey, DesignatedContact::getType));
+                    contact -> contact.getContactKey().getOfyKey(), DesignatedContact::getType));
 
     for (Key<ContactResource> contactKey : contactsToRoles.keySet()) {
       Set<RdapEntity.Role> roles =

core/src/main/java/google/registry/rdap/RdapSearchActionBase.java

@@ -221,10 +221,9 @@ public abstract class RdapSearchActionBase extends RdapActionBase {
    *
    * <p>This version handles a list of parameter values, all associated with the same name.
    *
-   * <p>Example: If the original parameters were "a=w&a=x&b=y&c=z", and this method is called with
-   * parameterName = "b" and parameterValues of "p" and "q", the result will be
-   * "a=w&a=x&c=z&b=p&b=q". The new values of parameter "b" replace the old ones.
-   *
+   * <p>Example: If the original parameters were "a=w&amp;a=x&amp;b=y&amp;c=z", and this method is
+   * called with parameterName = "b" and parameterValues of "p" and "q", the result will be
+   * "a=w&amp;a=x&amp;c=z&amp;b=p&amp;b=q". The new values of parameter "b" replace the old ones.
    */
   protected String getRequestUrlWithExtraParameter(
       String parameterName, List<String> parameterValues) {

core/src/main/java/google/registry/rde/DomainBaseToXjcConverter.java

@@ -15,13 +15,12 @@
 package google.registry.rde;
 
 import static com.google.common.base.Preconditions.checkState;
-import static google.registry.model.ofy.ObjectifyService.ofy;
+import static google.registry.persistence.transaction.TransactionManagerFactory.tm;
 
 import com.google.common.base.Ascii;
 import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableSet;
 import com.google.common.flogger.FluentLogger;
-import com.googlecode.objectify.Key;
 import google.registry.model.contact.ContactResource;
 import google.registry.model.domain.DesignatedContact;
 import google.registry.model.domain.DomainBase;
@@ -30,6 +29,7 @@ import google.registry.model.domain.secdns.DelegationSignerData;
 import google.registry.model.eppcommon.StatusValue;
 import google.registry.model.rde.RdeMode;
 import google.registry.model.transfer.TransferData;
+import google.registry.persistence.VKey;
 import google.registry.util.Idn;
 import google.registry.xjc.domain.XjcDomainContactAttrType;
 import google.registry.xjc.domain.XjcDomainContactType;
@@ -167,11 +167,11 @@ final class DomainBaseToXjcConverter {
         // o  An OPTIONAL <registrant> element that contain the identifier for
         //    the human or organizational social information object associated
         //    as the holder of the domain name object.
-        Key<ContactResource> registrant = model.getRegistrant();
+        VKey<ContactResource> registrant = model.getRegistrant();
         if (registrant == null) {
           logger.atWarning().log("Domain %s has no registrant contact.", domainName);
         } else {
-          ContactResource registrantContact = ofy().load().key(registrant).now();
+          ContactResource registrantContact = tm().load(registrant);
           checkState(
               registrantContact != null,
               "Registrant contact %s on domain %s does not exist",
@@ -304,7 +304,7 @@ final class DomainBaseToXjcConverter {
         "Contact key for type %s is null on domain %s",
         model.getType(),
         domainName);
-    ContactResource contact = ofy().load().key(model.getContactKey()).now();
+    ContactResource contact = tm().load(model.getContactKey());
     checkState(
         contact != null,
         "Contact %s on domain %s does not exist",

core/src/main/java/google/registry/rde/Ghostryde.java

@@ -120,9 +120,6 @@ public final class Ghostryde {
 
   /**
    * Creates a ghostryde file from an in-memory byte array.
-   *
-   * @throws PGPException
-   * @throws IOException
    */
   public static byte[] encode(byte[] data, PGPPublicKey key)
       throws IOException, PGPException {
@@ -137,9 +134,6 @@ public final class Ghostryde {
 
   /**
    * Deciphers a ghostryde file from an in-memory byte array.
-   *
-   * @throws PGPException
-   * @throws IOException
    */
   public static byte[] decode(byte[] data, PGPPrivateKey key)
       throws IOException, PGPException {

core/src/main/java/google/registry/rde/RdeUtil.java

@@ -46,9 +46,6 @@ public final class RdeUtil {
   /**
    * Look at some bytes from {@code xmlInput} to ensure it appears to be a FULL XML deposit and
    * then use a regular expression to extract the watermark timestamp which is returned.
-   *
-   * @throws IOException
-   * @throws XmlException
    */
   public static DateTime peekWatermark(BufferedInputStream xmlInput)
       throws IOException, XmlException {

core/src/main/java/google/registry/reporting/billing/BillingEmailUtils.java

@@ -34,7 +34,7 @@ import javax.mail.internet.InternetAddress;
 import org.joda.time.YearMonth;
 
 /** Utility functions for sending emails involving monthly invoices. */
-class BillingEmailUtils {
+public class BillingEmailUtils {
 
   private final SendEmailService emailService;
   private final YearMonth yearMonth;

core/src/main/java/google/registry/reporting/billing/GenerateInvoicesAction.java

@@ -43,8 +43,8 @@ import org.joda.time.YearMonth;
  * PublishInvoicesAction} to publish the subsequent output.
  *
  * <p>This action runs the {@link google.registry.beam.invoicing.InvoicingPipeline} beam template,
- * staged at gs://<projectId>-beam/templates/invoicing. The pipeline then generates invoices for the
- * month and stores them on GCS.
+ * staged at gs://&lt;projectId&gt;-beam/templates/invoicing. The pipeline then generates invoices
+ * for the month and stores them on GCS.
  */
 @Action(
     service = Action.Service.BACKEND,

core/src/main/java/google/registry/reporting/spec11/PublishSpec11ReportAction.java

@@ -53,7 +53,7 @@ import org.json.JSONException;
  * pipeline accordingly.
  *
  * <p>This calls {@link Spec11EmailUtils#emailSpec11Reports(LocalDate, SoyTemplateInfo, String,
- * Set)} on success or {@link Spec11EmailUtils#sendAlertEmail(String, String)} on failure.
+ * ImmutableSet)} on success or {@link Spec11EmailUtils#sendAlertEmail(String, String)} on failure.
  */
 @Action(
     service = Action.Service.BACKEND,

core/src/main/java/google/registry/request/HttpException.java

@@ -18,6 +18,7 @@ import static com.google.common.html.HtmlEscapers.htmlEscaper;
 
 import com.google.common.flogger.FluentLogger;
 import java.io.IOException;
+import java.util.logging.Level;
 import javax.servlet.http.HttpServletResponse;
 
 /** Base for exceptions that cause an HTTP error response. */
@@ -28,11 +29,18 @@ public abstract class HttpException extends RuntimeException {
 
   private static final FluentLogger logger = FluentLogger.forEnclosingClass();
 
+  private final Level logLevel;
+
   private final int responseCode;
 
-  protected HttpException(int responseCode, String message, Throwable cause) {
+  protected HttpException(int responseCode, String message, Throwable cause, Level logLevel) {
     super(message, cause);
     this.responseCode = responseCode;
+    this.logLevel = logLevel;
+  }
+
+  protected HttpException(int responseCode, String message, Throwable cause) {
+    this(responseCode, message, cause, Level.INFO);
   }
 
   public final int getResponseCode() {
@@ -57,7 +65,7 @@ public abstract class HttpException extends RuntimeException {
    */
   public final void send(HttpServletResponse rsp) throws IOException {
     rsp.sendError(getResponseCode(), htmlEscaper().escape(getMessage()));
-    logger.atInfo().withCause(getCause()).log("%s", this);
+    logger.at(logLevel).withCause(getCause()).log("%s", this);
   }
 
   /**
@@ -196,7 +204,7 @@ public abstract class HttpException extends RuntimeException {
   /** Exception that causes a 500 response. */
   public static final class InternalServerErrorException extends HttpException {
     public InternalServerErrorException(String message) {
-      super(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, message, null);
+      super(HttpServletResponse.SC_INTERNAL_SERVER_ERROR, message, null, Level.SEVERE);
     }
 
     public InternalServerErrorException(String message, Throwable cause) {

core/src/main/java/google/registry/request/RequestParameters.java

@@ -45,9 +45,9 @@ public final class RequestParameters {
    *
    * <ul>
    *   <li>/foo?bar=hello → hello
-   *   <li>/foo?bar=hello&bar=there → hello
+   *   <li>/foo?bar=hello&amp;bar=there → hello
    *   <li>/foo?bar= → 400 error (empty)
-   *   <li>/foo?bar=&bar=there → 400 error (empty)
+   *   <li>/foo?bar=&amp;bar=there → 400 error (empty)
    *   <li>/foo → 400 error (absent)
    * </ul>
    *

core/src/main/java/google/registry/schema/cursor/Cursor.java

@@ -16,10 +16,13 @@ package google.registry.schema.cursor;
 
 import static com.google.appengine.api.search.checkers.Preconditions.checkNotNull;
 
+import com.google.common.collect.ImmutableList;
 import google.registry.model.ImmutableObject;
 import google.registry.model.UpdateAutoTimestamp;
 import google.registry.model.common.Cursor.CursorType;
 import google.registry.schema.cursor.Cursor.CursorId;
+import google.registry.schema.replay.DatastoreEntity;
+import google.registry.schema.replay.SqlEntity;
 import google.registry.util.DateTimeUtils;
 import java.io.Serializable;
 import java.time.ZonedDateTime;
@@ -38,7 +41,7 @@ import org.joda.time.DateTime;
 @Entity
 @Table
 @IdClass(CursorId.class)
-public class Cursor {
+public class Cursor implements SqlEntity {
 
   @Enumerated(EnumType.STRING)
   @Column(nullable = false)
@@ -100,6 +103,11 @@ public class Cursor {
     return lastUpdateTime.getTimestamp();
   }
 
+  @Override
+  public ImmutableList<DatastoreEntity> toDatastoreEntities() {
+    return ImmutableList.of(); // Cursors are not converted since they are ephemeral
+  }
+
   static class CursorId extends ImmutableObject implements Serializable {
 
     public CursorType type;