This fixes the problem where the cordinator already knows about the
new schema and issues a read which uses new objects, but the replica
doesn't know those objects yet. The read will fail in this case. We
can avoid this if we propagate schema changes with reads, like we
already do for writes.
Message-Id: <20210205163422.414275-1-tgrabiec@scylladb.com>
It looks like the history of the flag begins in Cassandra's
https://issues.apache.org/jira/browse/CASSANDRA-7327 where it is
introduced to speedup tests by not needing to start the gossiper.
The thing is we always start gossiper in our cql tests, so the flag only
introduce noise. And, of course, since we want to move schema to use raft
it goes against the nature of the raft to be able to apply modification only
locally, so we better get rid of the capability ASAP.
Tests: units(dev, debug)
Message-Id: <20201230111101.4037543-2-gleb@scylladb.com>
There are 3 callers of this helper (cdc, migration manager and tests)
and all of them already have the database object at hands.
The argument will be used by next patch to remove call for global
storage proxy instance from make_update_indices_mutations.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
This PR purpose is to handle schema integrity issues that can arise in races involving materialized views.
The possibility of such integrity issues was found in #7420 , where a view schema was used for reading without
it's _base_info member initialized resulting in a segfault.
We handle this doing 3 things:
1. First guard against using an uninitialized base info - this will be considered as an internal error as it will indicate that
there is a path in our code that creates a view schema to be used for reads or writes but is not initializing the base info.
2. We allow the base info to be initialized also from partially matching base (most likely a newer one that this used to create the view).
3. We fix the suspected path that create such a view schema to initialize it. (in migration manager)
It is worth mentioning that this PR is a workaround to a probable design flaw in our materialized views which requires the base
table's information to be retrieved in the first place instead of just being self contained.
Refs #7420Closes#7469
* github.com:scylladb/scylla:
materialized views: add a base table reference if missing
view info: support partial match between base and view for only reading from view.
view info: guard against null dereference of the base info
schema pointers can be obtained from two distinct entities,
one is the database, those schema are obtained from the table
objects and the other is from the schema registry.
When a schema or a new schema is attached to a table object that
represents a base table for views, all of the corresponding attached
view schemas are guarantied to have their base info in sync.
However if an older schema is inserted into the registry by the
migratrion manager i.e loaded from other node, it will be
missing this info.
This becomes a problem when this schema is published through the
schema registry as it can be obtained for an obsolete read command
for example and then eventually cause a segmentation fault by null
dereferencing the _base_info ptr.
Refs #7420
The check was added to support migration from schema tables format v2
to v3. It was needed to handle the rolling upgrade from 2.x to 3.x
scylla version. Old nodes wouldn't recognize new schema mutations, so
the pull handler in v3 was changed to ignore requests from v2 nodes based
on their advertised SCHEMA_TABLES_VERSION gossip state.
This started to cause problems after 3b1ff90 (get rid of the seed
concept). The bootstrapping node sometimes would hang during boot
unable to reach schema agreement.
It's relevant that gossip exchanges about new nodes are unidirectional
(refs #2862).
It's also relevant that pulls are edge-triggered only (refs #7426).
If the bootstrapping node (A) is listed as a seed in one of the
existing node's (B) configuration then node A can be contacted before
it contacts node B. Node A may then send schema pull request to node B
before it learns about node A, and node B will assume it's an old node
and give an empty response. As a result, node A will end up with an
old schema.
The fix is to drop the check so that pull handler always responds with
the schema. We don't support upgrades from nodes using v2 schema
tables format anymore so this should be safe.
Fixes#7396
Tests:
- manual (ccm)
- unit (dev)
Message-Id: <1602612578-21258-1-git-send-email-tgrabiec@scylladb.com>
This patch introduces a new system table: `system.scylla_table_schema_history`,
which is used to keep track of column mappings for obsolete table
schema versions (i.e. schema becomes obsolete when it's being changed
by means of `CREATE TABLE` or `ALTER TABLE` DDL operations).
It is populated automatically when a new schema version is being
pulled from a remote in get_schema_definition() at migration_manager.cc
and also when schema change is being propagated to system schema tables
in do_merge_schema() at schema_tables.cc.
The data referring to the most recent table schema version is always
present. Other entries are garbage-collected when the corresponding
table schema version is obsoleted (they will be updated with a TTL equal
to `DEFAULT_GC_GRACE_SECONDS` on `ALTER TABLE`).
In case we failed to persist column mapping after a schema change,
missing entries will be recreated on node boot.
Later, the information from this table is used in `paxos_state::learn`
callback in case we have a mismatch between the most recent schema
version and the one that is stored inside the `frozen_mutation`
for the accepted proposal.
Such situation may arise under following circumstances:
1. The previous LWT operation crashed on the "accept" stage,
leaving behind a stale accepted proposal, which waits to be
repaired.
2. The table affected by LWT operation is being altered, so that
schema version is now different. Stored proposal now references
obsolete schema.
3. LWT query is retried, so that Scylla tries to repair the
unfinished Paxos round and apply the mutation in the learn stage.
When such mismatch happens, prior to that patch the stored
`frozen_mutation` is able to be applied only if we are lucky enough
and column_mapping in the mutation is "compatible" with the new
table schema.
It wouldn't work if, for example, the columns are reordered, or
some columns, which are referenced by an LWT query, are dropped.
With this patch we try to look up the column mapping for
the obsolete schema version, then upgrade the stored mutation
using obtained column mapping and apply an upgraded mutation instead.
* git@github.com:ManManson/scylla.git feature/table_schema_history_v7:
lwt: add column_mapping history persistence tests
schema: add equality operator for `column_mapping` class
lwt: store column_mapping's for each table schema version upon a DDL change
schema_tables: extract `fill_column_info` helper
frozen_mutation: introduce `unfreeze_upgrading` method
This patch introduces a new system table: `system.scylla_table_schema_history`,
which is used to keep track of column mappings for obsolete table
schema versions (i.e. schema becomes obsolete when it's being changed
by means of `CREATE TABLE` or `ALTER TABLE` DDL operations).
It is populated automatically when a new schema version is being
pulled from a remote in get_schema_definition() at migration_manager.cc
and also when schema change is being propagated to system schema tables
in do_merge_schema() at schema_tables.cc.
The data referring to the most recent table schema version is always
present. Other entries are garbage-collected when the corresponding
table schema version is obsoleted (they will be updated with a TTL equal
to `DEFAULT_GC_GRACE_SECONDS` on `ALTER TABLE`).
In case we failed to persist column mapping after a schema change,
missing entries will be recreated on node boot.
Later, the information from this table is used in `paxos_state::learn`
callback in case we have a mismatch between the most recent schema
version and the one that is stored inside the `frozen_mutation`
for the accepted proposal.
Such situation may arise under following circumstances:
1. The previous LWT operation crashed on the "accept" stage,
leaving behind a stale accepted proposal, which waits to be
repaired.
2. The table affected by LWT operation is being altered, so that
schema version is now different. Stored proposal now references
obsolete schema.
3. LWT query is retried, so that Scylla tries to repair the
unfinished Paxos round and apply the mutation in the learn stage.
When such mismatch happens, prior to that patch the stored
`frozen_mutation` is able to be applied only if we are lucky enough
and column_mapping in the mutation is "compatible" with the new
table schema.
It wouldn't work if, for example, the columns are reordered, or
some columns, which are referenced by an LWT query, are dropped.
With this patch we try to look up the column mapping for
the obsolete schema version, then upgrade the stored mutation
using obtained column mapping and apply an upgraded mutation instead.
In case we don't find a column_mapping we just return an error
from the learn stage.
Tests: unit(dev, debug), dtests(paxos_tests.py:TestPaxos.schema_mismatch_*_test)
Signed-off-by: Pavel Solodovnikov <pa.solodovnikov@scylladb.com>
"
This series follows the suggestion from https://github.com/scylladb/scylla/pull/7203#issuecomment-689499773 discussion and deprecates a number of cluster features. The deprecation does not remove any features from the strings sent via gossip to other nodes, but it removes all checks for these features from code, assuming that the checks are always true. This assumption is quite safe for features introduced over 2 years ago, because the official upgrade path only allows upgrading from a previous official release, and these feature bits were introduced many release cycles ago.
All deprecated features were picked from a `git blame` output which indicated that they come from 2018:
```git
e46537b7d3 2016-05-31 11:44:17 +0200 RANGE_TOMBSTONES_FEATURE = "RANGE_TOMBSTONES";
85c092c56c 2016-07-11 10:59:40 +0100 LARGE_PARTITIONS_FEATURE = "LARGE_PARTITIONS";
02bc0d2ab3 2016-12-09 22:09:30 +0100 MATERIALIZED_VIEWS_FEATURE = "MATERIALIZED_VIEWS";
67ca6959bd 2017-01-30 19:50:13 +0000 COUNTERS_FEATURE = "COUNTERS";
815c91a1b8 2017-04-12 10:14:38 +0300 INDEXES_FEATURE = "INDEXES";
d2a2a6d471 2017-08-03 10:53:22 +0300 DIGEST_MULTIPARTITION_READ_FEATURE = "DIGEST_MULTIPARTITION_READ";
ecd2bf128b 2017-09-01 09:55:02 +0100 CORRECT_COUNTER_ORDER_FEATURE = "CORRECT_COUNTER_ORDER";
713d75fd51 2017-09-14 19:15:41 +0200 SCHEMA_TABLES_V3 = "SCHEMA_TABLES_V3";
2f513514cc 2017-11-29 11:57:09 +0000 CORRECT_NON_COMPOUND_RANGE_TOMBSTONES = "CORRECT_NON_COMPOUND_RANGE_TOMBSTONES";
0be3bd383b 2017-12-04 13:55:36 +0200 WRITE_FAILURE_REPLY_FEATURE = "WRITE_FAILURE_REPLY";
0bab3e59c2 2017-11-30 00:16:34 +0000 XXHASH_FEATURE = "XXHASH";
fbc97626c4 2018-01-14 21:28:58 -0500 ROLES_FEATURE = "ROLES";
802be72ca6 2018-03-18 06:25:52 +0100 LA_SSTABLE_FEATURE = "LA_SSTABLE_FORMAT";
71e22fe981 2018-05-25 10:37:54 +0800 STREAM_WITH_RPC_STREAM = "STREAM_WITH_RPC_STREAM";
```
Tests: unit(dev)
manual(verifying with cqlsh that the feature strings are indeed still set)
"
Closes#7234.
* psarna-clean_up_features:
gms: add comments for deprecated features
gms: remove unused feature bits
streaming: drop checks for RPC stream support
roles: drop checks for roles schema support
service: drop checks for xxhash support
service: drop checks for write failure reply support
sstables: drop checks for non-compound range tombstones support
service: drop checks for v3 schema support
repair: drop checks for large partitions support
service: drop checks for digest multipartition read support
sstables: drop checks for correct counter order support
cql3: drop checks for materialized views support
cql3: drop checks for counters support
cql3: drop checks for indexing support
Migration manager installs several feature change listeners:
if (this_shard_id() == 0) {
_feature_listeners.push_back(_feat.cluster_supports_view_virtual_columns().when_enabled(update_schema));
_feature_listeners.push_back(_feat.cluster_supports_digest_insensitive_to_expiry().when_enabled(update_schema));
_feature_listeners.push_back(_feat.cluster_supports_cdc().when_enabled(update_schema));
_feature_listeners.push_back(_feat.cluster_supports_per_table_partitioners().when_enabled(update_schema));
}
They will call update_schema_version_and_announce() when features are enabled, which does this:
return update_schema_version(proxy, features).then([] (utils::UUID uuid) {
return announce_schema_version(uuid);
});
So it first updates the schema version and then publishes it via
gossip in announce_schema_version(). It is possible that the
announce_schema_version() part of the first schema change will be
deferred and will execute after the other four calls to
update_schema_version_and_announce(). It will install the old schema
version in gossip instead of the more recent one.
The fix is to serialize schema digest calculation and publishing.
Refs #7200
There are 4 places that call this helper:
- storage proxy. Callers are rpc verb handlers and already have the proxy
at hands from which they can get the messaging service instance
- repair. There's local-global messaging instance at hands, and the caller
is in verb handler too
- streaming. The caller is verb handler, which is unregistered on stop, so
the messaging service instance can be captured
- migration manager itself. The caller already uses "this", so the messaging
service instance can be get from it
The better approach would be to make get_schema_definition be the method of
migration_manager, but the manager is stopped for real on shutdown, thus
referencing it from the callers might not be safe and needs revisiting. At
the same time the messaging service is always alive, so using its reference
is safe.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Most of those places are either non-static migration_manager methods.
Plus one place where the local service instance is already at hands.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
The local migration manager instance is already available at caller, so
we can call a method on it. This is to facilitate next patching.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
The user of this verb is migration manager, so the handler must be it as well.
The hander code now explicitly gets global proxy. This call is safe, as proxy
is not stopped nowadays. In the future we'll need to revisit the relation
between migration - proxy - stats anyway.
The use of local migration manager is safe, as it happens in verb handler which
is unregistered and is waited to be completed on migration manager stop.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
C++20 introduced `contains` member functions for maps and sets for
checking whether an element is present in the collection. Previously
the code pattern looked like:
<collection>.find(<element>) != <collection>.end()
In C++20 the same can be expressed with:
<collection>.contains(<element>)
This is not only more concise but also expresses the intend of the code
more clearly.
This commit replaces all the occurences of the old pattern with the new
approach.
Tests: unit(dev)
Signed-off-by: Piotr Jastrzebski <piotr@scylladb.com>
Message-Id: <f001bbc356224f0c38f06ee2a90fb60a6e8e1980.1597132302.git.piotr@scylladb.com>
The schema_tables.hh -> migration_manager.hh couple seems to work as one
of "single header for everyhing" creating big blot for many seemingly
unrelated .hh's.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
The seastar api v4 changes the return type of when_all_succeed. This
patch adds discard_result when that is best solution to handle the
change.
This doesn't do the actual update to v4 since there are still a few
issues left to fix in seastar. A patch doing just the update will
follow.
Signed-off-by: Rafael Ávila de Espíndola <espindola@scylladb.com>
Message-Id: <20200617233150.918110-1-espindola@scylladb.com>
sync_schema is supposed to make sure that this node knows about all
schema changes known by "nodes" that were made prior to this call.
Currently, when a node is down, the sync is sliently skipped.
To fix, add a flag to migration_task::run_may_throw to indicate that it
should fail if a node is down.
Fixes#4791
sync_schema is supposed to make sure that this node knows about all
schema changes known by "nodes" that were made prior to this call.
Currently, when a node is down, the sync is sliently skipped.
To fix, add a flag to migration_task::run_may_throw to indicate that it
should fail if a node is down.
Fixes#4791
The call for merge_schema_from in some cases is run in the
background and thus is not aborted/waited on shutdown. This
may result in use-after-free one of which is
merge_schema_from
-> read_schema_for_keyspace
-> db::system_keyspace::query
-> storage_proxy::query
-> query_partition_key_range_concurrent
in the latter function the proxy._token_metadata is accessed,
while the respective object can be already free (unlike the
storage_proxy itself that's still leaked on shutdown).
Related bug: #5903, #5999 (cannot reproduce though)
Tests: unit(dev), manual start-stop
dtest(consistency.TestConsistency, dev)
dtest(schema_management, dev)
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Reviewed-by: Pekka Enberg <penberg@scylladb.com>
Message-Id: <20200316150348.31118-1-xemul@scylladb.com>
Following commits make it possible to set a specific
partitioner for a table. We want to persist that information
and include it into schema digest. For that a new column
in scylla_tables is needed. This commit adds such column.
We add the new column to scylla_tables because it's a Scylla
specific extension.
Signed-off-by: Piotr Jastrzebski <piotr@scylladb.com>
The maybe_schedule_schema_pull waits for schema_tables_v3 to
become available. This is unsafe in case migration manager
goes away before the feature is enabled.
Fix this by subscribing on feature with feature::listener and
waiting for condition variable in maybe_schedule_schema_pull.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
The sleep is interrupted with the abort source, the "wait" part
is done with the existing _background_tasks gate. Also we need
to make sure the gate stays alive till the end of the function,
so make use of the async_sharded_service (migration manager is
already such).
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
The goal is to have token_metadata reference intide the
keyspace_metadata.validate method. This can be acheived
by doing the validation through the database reference
which is "at hands" in migration_manager.
While at it, merge the validation with exists/not-exists
checks done in the same places.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
This unties migration_manager from storage_service thus breaking
the circular dependency between these two.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
This templates the code for listener_vector, renames it to
atomic_vector and moves it to the utils directory.
Signed-off-by: Rafael Ávila de Espíndola <espindola@scylladb.com>
Before this patch the iterations over migration_notifier::_listeners
could race with listeners being added and removed.
The addition side is not modified, since it is common to add a
listener during construction and it would require a fairly big
refactoring. Instead, the iteration is modified to use indexes instead
of iterators so that it is still valid if another listener is added
concurrently.
For removal we use a rw lock, since removing an element invalidates
indexes too. There are only a few places that needed refactoring to
handle unregister_listener returning a future<>, so this is probably
OK.
Fixes#5541.
Signed-off-by: Rafael Ávila de Espíndola <espindola@scylladb.com>
Message-Id: <20200120192819.136305-1-espindola@scylladb.com>
The factory is purely a state-less thing, there is no difference what
instance of it to use, so we may omit referencing the storage_service
in passive_announce
This is 2nd simple migration_manager -> storage_service link to cut
(more to come later).
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
There are several places where migration_manager needs storage_service
reference to get the database from, thus forming the mutual dependency
between them. This is the simplest case where the migration_manager
link to the storage_service can be cut -- the databse reference can be
obtained from storage_proxy instead.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
The _listeners list on migration_manager class and the corresponding
notify_xxx helpers have nothing to do with the its instances, they
are just transport for notification delivery.
At the same time some services need the migration manager to be alive
at their stop time to unregister from it, while the manager itself
may need them for its needs.
The proposal is to move the migration notifier into a complete separate
sharded "service". This service doesn't need anything, so it's started
first and stopped last.
While it's not effectively a "migration" notifier, we inherited the name
from Cassandra and renaming it will "scramble neurons in the old-timers'
brains but will make it easier for newcomers" as Avi says.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Addition of cdc column in scylla_tables changes how schema
digests are calculated, and affect the ABI of schema update
messages (adding a column changes other columns' indexes
in frozen_mutation).
To fix this, extend the schema_tables mechanism with support
for the cdc column, and adjust schemas and mutations to remove
that column when sending schemas during upgrade.
Signed-off-by: Piotr Jastrzebski <piotr@scylladb.com>
Schema is node-global, update_schema_version_and_announce() updates
all shards. We don't need to recalculate it from every shard, so
install the listeners only on shard 0. Reduces noise in the logs.
Message-Id: <1574872860-27899-1-git-send-email-tgrabiec@scylladb.com>
Merged pull request https://github.com/scylladb/scylla/pull/5366 from Calle Wilund:
Moves schema creation/alter/drop awareness to use new "before" callbacks from
migration manager, and adds/modifies log and streams table as part of the base
table modification.
Makes schema changes semi-atomic per node. While this does not deal with updates
coming in before a schema change has propagated cluster, it now falls into the
same pit as when this happens without CDC.
Added side effect is also that now schemas are transparent across all subsystems,
not just cql.
Patches:
cdc_test: Add small test for altering base schema (add column)
cdc: Handle schema changes via migration manager callbacks
migration_manager: Invoke "before" callbacks for table operations
migration_listener: Add empty base class and "before" callbacks for tables
cql_test_env: Include cdc service in cql tests
cdc: Add sharded service that does nothing.
cdc: Move "options" to separate header to avoid to much header inclusion
cdc: Remove some code from header
Before stopping the db itself, stop the migration service.
It must be stopped before RPC, but RPC is not stopped yet
itself, so we should be safe here.
Here's the tail of the resulting logs:
INFO 2019-11-20 11:22:35,193 [shard 0] init - shutdown migration manager
INFO 2019-11-20 11:22:35,193 [shard 0] migration_manager - stopping migration service
INFO 2019-11-20 11:22:35,193 [shard 1] migration_manager - stopping migration service
INFO 2019-11-20 11:22:35,193 [shard 0] init - Shutdown database started
INFO 2019-11-20 11:22:35,193 [shard 0] init - Shutdown database finished
INFO 2019-11-20 11:22:35,193 [shard 0] init - stopping prometheus API server
INFO 2019-11-20 11:22:35,193 [shard 0] init - Scylla version 666.development-0.20191120.25820980f shutdown complete.
Also -- stop the mm on drain before the commitlog it stopped.
[Tomasz: mm needs the cl because pulling schema changes from other nodes
involves applying them into the database. So cl/db needs to be
stopped after mm is stopped.]
The drain logs would look like
...
INFO 2019-11-25 11:00:40,562 [shard 0] migration_manager - stopping migration service
INFO 2019-11-25 11:00:40,562 [shard 1] migration_manager - stopping migration service
INFO 2019-11-25 11:00:40,563 [shard 0] storage_service - DRAINED:
and then on stop
...
INFO 2019-11-25 11:00:46,427 [shard 0] init - shutdown migration manager
INFO 2019-11-25 11:00:46,427 [shard 0] init - Shutdown database started
INFO 2019-11-25 11:00:46,427 [shard 0] init - Shutdown database finished
INFO 2019-11-25 11:00:46,427 [shard 0] init - stopping prometheus API server
INFO 2019-11-25 11:00:46,427 [shard 0] init - Scylla version 666.development-0.20191125.3eab6cd54 shutdown complete.
Fixes#5300
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Message-Id: <20191125080605.7661-1-xemul@scylladb.com>
With this it is possible to create user defined functions and
aggregates and they are saved to disk and the schema change is
propagated.
It is just not possible to call them yet.
Signed-off-by: Rafael Ávila de Espíndola <espindola@scylladb.com>
The verbs are:
* DEFINITIONS_UPDATE (push)
* MIGRATION_REQUEST (pull)
Support was added in a backward-compatible way. The push verb, sends
both the old frozen mutation parameter, and the new optional canonical
mutation parameter. It is expected that new nodes will use the latter,
while old nodes will fall-back to the former. The pull verb has a new
optional `options` parameter, which for now contains a single flag:
`remote_supports_canonical_mutation_retval`. This flag, if set, means
that the remote node supports the new canonical mutation return value,
thus the old frozen mutations return value can be left empty.
