For counter updates, use a counter ID that is constructed from the
node's rack instead of the node's host ID.
A rack can have at most two active tablet replicas at a time: a single
normal tablet replica, and during tablet migration there are two active
replicas, the normal and pending replica. Therefore we can have two
unique counter IDs per rack that are reused by all replicas in the rack.
We construct the counter ID from the rack UUID, which is constructed
from the name "dc:rack". The pending replica uses a deterministic
variation of the rack's counter ID by negating it.
This improves the performance and size of counter cells by having less
unique counter IDs and less counter shards in a counter cell.
Previously the number of counter shards was the number of different
host_id's that updated the counter, which can be typically the number of
nodes in the cluster and continue growing indefinitely when nodes are
replaced. with the rack-based counter id the number of counter shards
will be at most twice the number of different racks (including removed
racks, which should not be significant).
Fixes SCYLLADB-356
backport not needed - an enhancement
Closesscylladb/scylladb#28901
* github.com:scylladb/scylladb:
docs/dev: add counters doc
counters: reuse counter IDs by rack
Cassandra's native vector index type is StorageAttachedIndex (SAI). Libraries such as CassIO, LangChain, and LlamaIndex generate `CREATE CUSTOM INDEX` statements using the SAI class name. Previously, ScyllaDB rejected these with "Non-supported custom class".
This PR adds compatibility so that SAI-style CQL statements work on ScyllaDB without modification.
1. **test: enable SAI_VECTOR_ALLOW_CUSTOM_PARAMETERS for Cassandra tests**
Enables the `SAI_VECTOR_ALLOW_CUSTOM_PARAMETERS` Cassandra system property so that `search_beam_width` tests pass against Cassandra 5.0.7.
2. **test: modernize vector index test comments and fix xfail**
Updates test comments from "Reproduces" to "Validates fix for" for clarity, and converts the `test_ann_query_with_pk_restriction` xfail into a stripped-down CREATE INDEX syntax test (removing unused INSERT/SELECT lines). Removes the redundant `test_ann_query_with_non_pk_restriction` test.
3. **cql: add Cassandra SAI (StorageAttachedIndex) compatibility**
Core implementation: the SAI class name is detected and translated to ScyllaDB's native `vector_index`. The fully-qualified class name (`org.apache.cassandra.index.sai.StorageAttachedIndex`) requires exact case; short names (`StorageAttachedIndex`, `sai`) are matched case-insensitively — matching Cassandra's behavior. Non-vector and multi-column SAI targets are rejected with clear errors. Adds `skip_on_scylla_vnodes` fixture, SAI compatibility docs, and the Cassandra compatibility table entry (split into "SAI general" vs "SAI for vector search").
4. **cql: accept source_model option for Cassandra SAI compatibility**
The `source_model` option is a Cassandra SAI property used by Cassandra libraries (e.g., CassIO) to tag vector indexes with the name of the embedding model. ScyllaDB accepts it for compatibility but does not use it — the validator is a no-op lambda. The option is preserved in index metadata and returned in DESCRIBE INDEX output.
- `cql3/statements/create_index_statement.cc`: SAI class detection and rewriting logic
- `index/secondary_index_manager.cc`: case-insensitive class name lookup (lowercasing restored before `classes.find()`)
- `index/vector_index.cc`: `source_model` accepted as a valid option with no-op validator
- `docs/cql/secondary-indexes.rst`: SAI compatibility documentation with `source_model` table row
- `docs/using-scylla/cassandra-compatibility.rst`: SAI entry split into general (not supported) and vector search (supported)
- `test/cqlpy/conftest.py`: `scylla_with_tablets` renamed to `skip_on_scylla_vnodes`
- `test/cqlpy/test_vector_index.py`: SAI tests inlined (no constants), `check_bad_option()` helper for numeric validation, uppercase class name test, merged `source_model` tests with DESCRIBE check
| Backend | Passed | Skipped | Failed |
|--------------------|--------|---------|--------|
| ScyllaDB (dev) | 42 | 0 | 0 |
| Cassandra 5.0.7 | 16 | 26 | 0 |
None: new feature.
Fixes: SCYLLADB-239
Closesscylladb/scylladb#28645
* github.com:scylladb/scylladb:
cql: accept source_model option and show options in DESCRIBE
cql: add Cassandra SAI (StorageAttachedIndex) compatibility
test: modernize vector index test comments and fix xfail
test: enable SAI_VECTOR_ALLOW_CUSTOM_PARAMETERS for Cassandra tests
Accept the Cassandra SAI 'source_model' option for vector indexes.
This option is used by Cassandra libraries (e.g., CassIO, LangChain)
to tag vector indexes with the name of the embedding model that
produced the vectors.
ScyllaDB does not use the source_model value but stores it and
includes it in the DESCRIBE INDEX output for Cassandra compatibility.
Additionally, extend vector_index::describe() to emit a
WITH OPTIONS = {...} clause containing all user-provided index options
(filtering out system keys: target, class_name, index_version).
This makes options like similarity_function, source_model, etc.
visible in DESCRIBE output.
Libraries such as CassIO, LangChain, and LlamaIndex create vector
indexes using Cassandra's StorageAttachedIndex (SAI) class name.
This commit lets ScyllaDB accept these statements without modification.
When a CREATE CUSTOM INDEX statement specifies an SAI class name on a
vector column, ScyllaDB automatically rewrites it to the native
vector_index implementation. Accepted class names (case-insensitive):
- org.apache.cassandra.index.sai.StorageAttachedIndex
- StorageAttachedIndex
- sai
SAI on non-vector columns is rejected with a clear error directing
users to a secondary index instead.
The SAI detection and rewriting logic is extracted into a dedicated
static function (maybe_rewrite_sai_to_vector_index) to keep the
already-long validate_while_executing method manageable.
Multi-column (local index) targets and nonexistent columns are
skipped with continue — the former are treated as filtering columns
by vector_index::check_target(), and the latter are caught later by
vector_index::validate().
Tests that exercise features common to both backends (basic creation,
similarity_function, IF NOT EXISTS, bad options, etc.) now use the
SAI class name with the skip_on_scylla_vnodes fixture so they run
against both ScyllaDB and Cassandra. ScyllaDB-specific tests continue
to use USING 'vector_index' with scylla_only.
Every time someone modifies the build system — adding a source file, changing a compilation flag, or wiring a new test — the change tends to land in only one of our two build systems (configure.py or CMake). Over time this causes three classes of problems:
1. **CMake stops compiling entirely.** Missing defines, wrong sanitizer flags, or misplaced subdirectory ordering cause hard build failures that are only discovered when someone tries to use CMake (e.g. for IDE integration).
2. **Missing build targets.** Tests or binaries present in configure.py are never added to CMake, so `cmake --build` silently skips them. This PR fixes several such cases (e.g. `symmetric_key_test`, `auth_cache_test`, `sstable_tablet_streaming`).
3. **Missing compilation units in targets.** A `.cc` file is added to a test binary in one system but not the other, causing link errors or silently omitted test coverage.
To fix the existing drift and prevent future divergence, this series:
**Adds a build-system comparison script**
(`scripts/compare_build_systems.py`) that configures both systems into a temporary directory, parses their generated `build.ninja` files, and compares per-file compilation flags, link target sets, and per-target libraries. configure.py is treated as the baseline; CMake must match it. The script supports a `--ci` mode suitable for gating PRs that touch
build files.
**Fixes all current mismatches** found by the script:
- Mode flag alignment in `mode.common.cmake` and `mode.Coverage.cmake`
(sanitizer flags, `-fno-lto`, stack-usage warnings, coverage defines).
- Global define alignment (`SEASTAR_NO_EXCEPTION_HACK`, `XXH_PRIVATE_API`,
`BOOST_ALL_DYN_LINK`, `SEASTAR_TESTING_MAIN` placement).
- Seastar build configuration (shared vs static per mode, coverage
sanitizer link options).
- Abseil sanitizer flags (`-fno-sanitize=vptr`).
- Missing test targets in `test/boost/CMakeLists.txt`.
- Redundant per-test flags now covered by global settings.
- Lua library resolution via a custom `cmake/FindLua.cmake` using
pkg-config, matching configure.py's approach.
**Adds documentation** (`docs/dev/compare-build-systems.md`) describing how to run the script and interpret its output.
No backport needed — this is build infrastructure improvement only.
Closesscylladb/scylladb#29273
* github.com:scylladb/scylladb:
scripts: remove lua library rename workaround from comparison script
cmake: add custom FindLua using pkg-config to match configure.py
test/cmake: add missing tests to boost test suite
test/cmake: remove per-test LTO disable
cmake: add BOOST_ALL_DYN_LINK and strip per-component defines
cmake: move SEASTAR_TESTING_MAIN after seastar and abseil subdirs
cmake: add -fno-sanitize=vptr for abseil sanitizer flags
cmake: align Seastar build configuration with configure.py
cmake: align global compile defines and options with configure.py
cmake: fix Coverage mode in mode.Coverage.cmake
cmake: align mode.common.cmake flags with configure.py
configure.py: add sstable_tablet_streaming to combined_tests
docs: add compare-build-systems.md
scripts: add compare_build_systems.py to compare ninja build files
Add a documentation of the counters feature implementation in
docs/dev/counters.md.
The documentation is taken from the wiki and updated according to the
current state of the code - legacy details are removed, and a section
about the counter id is added.
- Document Alternator (DynamoDB-compatible API) auditing support in
the operator-facing auditing guide (docs/operating-scylla/security/auditing.rst)
- Cover operation-to-category mapping, operation field format,
keyspace/table filtering, and audit log examples
- Document the audit_tables=alternator.<table> shorthand format
- Minor wording improvements throughout (Scylla -> ScyllaDB,
clarify default audit backend)
Closesscylladb/scylladb#29231
Fixes#29043 with the following docs changes:
- docs/dev/system-keyspaces.md: Added a new file that documents all keyspaces created internally
Closesscylladb/scylladb#29044
This commit removes references ScyllaDB versions ("Since x.y")
from the ScyllaDB documentation on Docker Hub, as they are
redundant and confusing (some versions are super ancient).
Fixes SCYLLADB-1212
Closesscylladb/scylladb#29204
The rack option was fully implemented in the code but omitted from
both docs/operating-scylla/admin.rst and conf/scylla.yaml comments.
Closesscylladb/scylladb#29239
Queries against local vector indexes were failing with the error:
```ANN ordering by vector requires the column to be indexed using 'vector_index'```
This was a regression introduced by 15788c3734, which incorrectly
assumed the first column in the targets list is always the vector column.
For local vector indexes, the first column is the partition key, causing
the failure.
Previously, serialization logic for the target index option was shared
between vector and secondary indexes. This is no longer viable due to
the introduction of local vector indexes and vector indexes with filtering
columns, which have different target format.
This commit introduces a dedicated JSON-based serialization format for
vector index targets, identifying the target column (tc), filtering
columns (fc), and partition key columns (pk). This ensures unambiguous
serialization and deserialization for all vector index types.
This change is backward compatible for regular vector indexes. However,
it breaks compatibility for local vector indexes and vector indexes with
filtering columns created in version 2026.1.0. To mitigate this, usage
of these specific index types will be blocked in the 2026.1.0 release
by failing ANN queries against them in vector-store service.
Fixes: SCYLLADB-895
Backport to 2026.1 is required as this issue occurs also on this branch.
Closesscylladb/scylladb#28862
* github.com:scylladb/scylladb:
index: fix DESC INDEX for vector index
vector_search: test: refactor boilerplate setup
vector_search: fix SELECT on local vector index
index: test: vector index target option serialization test
index: test: secondary index target option serialization test
This issue adds the upgrade guide for all patch releases within 2026.x major release.
In addition, it fixes the link to Upgrade Policy in the 2025.x-to-2026.1 upgrade guide.
Fixes SCYLLADB-1247
Closesscylladb/scylladb#29307
This PR introduces the vnodes-to-tablets migration procedure, which enables converting an existing vnode-based keyspace to tablets.
The migration is implemented as a manual, operator-driven process executed in several stages. The core idea is to first create tablet maps with the same token boundaries and replica hosts as the vnodes, and then incrementally convert the storage of each node to the tablets layout. At a high level, the procedure is the following:
1. Create tablet maps for all tables in the keyspace.
2. Sequentially upgrade all nodes from vnodes to tablets:
1. Mark a node for upgrade in the topology state.
2. Restart the node. During startup, while the node is offline, it reshards the SSTables on vnode boundaries and switches to a tablet ERM.
3. Wait for the node to return online before proceeding to the next node.
4. Finalize the migration:
1. Update the keyspace schema to mark it as tablet-based.
2. Clear the group0 state related to the migration.
From the client's perspective, the migration is online; the cluster can still serve requests on that keyspace, although performance may be temporarily degraded.
During the migration, some nodes use vnode ERMs while others use tablet ERMs. Cluster-level algorithms such as load balancing will treat the keyspace's tables as vnode-based. Once migration is finalized, the keyspace is permanently switched to tablets and cannot be reverted back to vnodes. However, a rollback procedure is available before finalization.
The patch series consists of:
* Load balancer adjustments to ignore tablets belonging to a migrating keyspace.
* A new vnode-based resharding mode, where SSTables are segregated on vnode boundaries rather than with the static sharder.
* A new per-node `intended_storage_mode` column in `system.topology`. Represents migration intent (whether migration should occur on restart) and direction.
* Four new REST endpoints for driving the migration (start, node upgrade/downgrade, finalize, status), along with `nodetool` wrappers. The finalization is implemented as a global topology request.
* Wiring of the migration process into the startup logic: the `distributed_loader` determines a migrating table's ERM flavor from the `intended_storage_mode` and the ERM flavor determines the `table_populator`'s resharding mode. Token metadata changes have been adjusted to preserve the ERM flavor.
* Cluster tests for the migration process.
Fixes SCYLLADB-722.
Fixes SCYLLADB-723.
Fixes SCYLLADB-725.
Fixes SCYLLADB-779.
Fixes SCYLLADB-948.
New feature, no backport is needed.
Closesscylladb/scylladb#29065
* github.com:scylladb/scylladb:
docs: Add ops guide for vnodes-to-tablets migration
test: cluster: Add test for migration of multiple keyspaces
test: cluster: Add test for error conditions
test: cluster: Add vnodes->tablets migration test (rollback)
test: cluster: Add vnodes->tablets migration test (1 table, 3 nodes)
test: cluster: Add vnodes->tablets migration test (1 table, 1 node)
scylla-nodetool: Add migrate-to-tablets subcommand
api: Add REST endpoint for vnode-to-tablet migration status
api: Add REST endpoint for migration finalization
topology_coordinator: Add `finalize_migration` request
database: Construct migrating tables with tablet ERMs
api: Add REST endpoint for upgrading nodes to tablets
api: Add REST endpoint for starting vnodes-to-tablets migration
topology_state_machine: Add intended_storage_mode to system.topology
distributed_loader: Wire vnode-based resharding into table populator
replica: Pick any compaction group for resharding
compaction: resharding_compaction: add vnodes_resharding option
storage_service: Preserve ERM flavor of migrating tables
tablet_allocator: Exclude migrating tables from load balancing
feature_service: Add vnodes_to_tablets_migrations feature
As discussed with @ScyllaPiotr in
https://github.com/scylladb/scylladb/pull/29232, the doc about to be
removed is just:
> Looking at history, I think this audit.md is a design doc: scylladb/scylla-enterprise@87a5c19, for which the feature has been implemented differently, eventually, and was created around the time when design docs, apparently, where stored within the repository itself. So for me it's some trash (sorry for strong language) that can be safely removed.
Closesscylladb/scylladb#29316
Queries against local vector indexes were failing with the error:
"ANN ordering by vector requires the column to be indexed using 'vector_index'"
This was a regression introduced by 15788c3734, which incorrectly
assumed the first column in the targets list is always the vector column.
For local vector indexes, the first column is the partition key, causing
the failure.
Previously, serialization logic for the target index option was shared
between vector and secondary indexes. This is no longer viable due to
the introduction of local vector indexes and vector indexes with filtering
columns, which have different target format.
This commit introduces a dedicated JSON-based serialization format for
vector index targets, identifying the target column (tc), filtering
columns (fc), and partition key columns (pk). This ensures unambiguous
serialization and deserialization for all vector index types.
This change is backward compatible for regular vector indexes. However,
it breaks compatibility for local vector indexes and vector indexes with
filtering columns created in version 2026.1.0. To mitigate this, usage
of these specific index types will be blocked in the 2026.1.0 release
by failing ANN queries against them in vector-store service.
Fixes: SCYLLADB-895
Target option serialization must remain stable for backward compatibility.
The index is restored from this property on startup, so unintentional
changes to the serialization schema can break indexes after upgrade.
The vnodes-to-tablets migration is a manual procedure, so instructions
need to be provided to the users.
Signed-off-by: Nikos Dragazis <nikolaos.dragazis@scylladb.com>
Document the purpose, usage, and examples for
scripts/compare_build_systems.py which compares the configure.py
and CMake build systems by parsing their ninja build files.
Part of the vnodes-to-tablets migration is to reshard the SSTables of
each node on vnode boundaries. Resharding is a heavy operation that
runs on startup while the node is offline. Since nodes can restart
for unexpected reasons, we need a flag to do it in a controllable way.
We also need the ability to roll back the migration, which requires
resharding in the opposite direction. This means a node must be aware of
the intended migration direction.
To address both requirements, this patch introduces a new column,
intended_storage_mode, in system.topology. A non-null value indicates
that a node should perform a migration and specifies the migration
direction.
Signed-off-by: Nikos Dragazis <nikolaos.dragazis@scylladb.com>
This patch series introduces a new documentation for exiting guardrails.
Moreover:
- Warning / failure messages of recently added write CL guardrails (SCYLLADB-259) are rephrased, so all guardrails have similar messages.
- Some new tests are added, to help verify the correctness of the documentation and avoid situations where the documentation and implementation diverge.
Fixes: [SCYLLADB-257](https://scylladb.atlassian.net/browse/SCYLLADB-257)
No backport, just new docs and tests.
[SCYLLADB-257]: https://scylladb.atlassian.net/browse/SCYLLADB-257?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQClosesscylladb/scylladb#29011
* github.com:scylladb/scylladb:
test: add new guardrail tests matching documentation scenarios
test: add metric assertions to guardrail replication strategy tests
test: use regex matching in guardrail replication strategy tests
test: extract ks_opts helper in test_guardrail_replication_strategy
docs: document CQL guardrails
cql: improve write consistency level guardrail messages
Introduce an initial and experimental implementation of an alternative log-structured storage engine for key-value tables.
Main flows and components:
* The storage is composed of 32MB files, each file divided to segments of size 128k. We write to them sequentially records that contain a mutation and additional metadata. Records are written to a buffer first and then written to the active segment sequentially in 4k sized blocks.
* The primary index in memory maps keys to their location on disk. It is a B-tree per-table that is ordered by tokens, similar to a memtable.
* On reads we calculate the key and look it up in the primary index, then read the mutation from disk with a single disk IO.
* On writes we write the record to a buffer, wait for it to be written to disk, then update the index with the new location, and free the previous record.
* We track the used space in each segment. When overwriting a record, we increase the free space counter for the segment of the previous record that becomes dead. We store the segments in a histogram by usage.
* The compaction process takes segments with low utilization, reads them and writes the live records to new segments, and frees the old segments.
* Segments are initially "mixed" - we write to the active segment records from all tables and all tablets. The "separator" process rewrites records from mixed segments into new segments that are organized by compaction groups (tablets), and frees the mixed segments. Each write is written to the active segment and to a separator buffer of the compaction group, which is eventually flushed to a new segment in the compaction group.
Currently this mode is experimental and requires an experimental flag to be enabled.
Some things that are not supported yet are strong consistency, tablet migration, tablet split/merge, big mutations, tombstone gc, ttl.
to use, add to config:
```
enable_logstor: true
experimental_features:
- logstor
```
create a table:
```
CREATE TABLE ks.t(pk int PRIMARY KEY, a int, v text) WITH storage_engine = 'logstor';
```
INSERT, SELECT, DELETE work as expected
UPDATE not supported yet
no backport - new feature
Closesscylladb/scylladb#28706
* github.com:scylladb/scylladb:
logstor: trigger separator flush for buffers that hold old segments
docs/dev: add logstor documentation
logstor: recover segments into compaction groups
logstor: range read
logstor: change index to btree by token per table
logstor: move segments to replica::compaction_group
db: update dirty mem limits dynamically
logstor: track memory usage
logstor: logstor stats api
logstor: compaction buffer pool
logstor: separator: flush buffer when full
logstor: hold segment until index updates
logstor: truncate table
logstor: enable/disable compaction per table
logstor: separator buffer pool
test: logstor: add separator and compaction tests
logstor: segment and separator barrier
logstor: separator debt controller
logstor: compaction controller
logstor: recovery: recover mixed segments using separator
logstor: wait for pending reads in compaction
logstor: separator
logstor: compaction groups
logstor: cache files for read
logstor: recovery: initial
logstor: add segment generation
logstor: reserve segments for compaction
logstor: index: buckets
logstor: add buffer header
logstor: add group_id
logstor: record generation
logstor: generation utility
logstor: use RIPEMD-160 for index key
test: add test_logstor.py
api: add logstor compaction trigger endpoint
replica: add logstor to db
schema: add logstor cf property
logstor: initial commit
db: disable tablet balancing with logstor
db: add logstor experimental feature flag
This PR fixes the Installation page:
- Replaces `http `with `https `in the download command.
- Replaces the Open Source example from the Installation section for CentOS (we overlooked this example before).
Fixes https://github.com/scylladb/scylladb/issues/29087
Fixes https://github.com/scylladb/scylladb/issues/29087
This update affects all supported versions and should be backported as a bug fix.
Closesscylladb/scylladb#29088
* github.com:scylladb/scylladb:
doc: remove the Open Source Example from Installation
doc: replace http with https in the installation instructions
The Web Installer page includes instructions to install the old pre-2025.1 Enterprise versions,
which are no longer supported (since we released 2026.1).
This commit removes those redundant and misleading instructions.
Fixes https://github.com/scylladb/scylladb/issues/29099Closesscylladb/scylladb#29103
Document that `SELECT ... WHERE` clause currently accepts only conjunctions
of relations joined by `AND` (`OR` is not supported), and that
parentheses cannot be used to group boolean subexpressions.
Add an unsupported query example and point readers to equivalent `IN`
rewrites when applicable.
This problem has been raised by one of our users in
https://forum.scylladb.com/t/error-parsing-query-or-unsupported-statement/5299,
and while one could infer answer to user's question by looking at the
syntax of the `SELECT ... WHERE`, it's not immediately obvious to
non-advanced users, so clarifying these concepts is justified.
Fixes: SCYLLADB-1116
Closesscylladb/scylladb#29100
This commit replaces the Open Soruce example from the Installation section for CentOS.
We updated the example for Ubuntu, but not for CentOS.
We don't want to have any Open Source information in the docs.
Fixes https://github.com/scylladb/scylladb/issues/29087
Remove outdated references to filtering on columns provided in the
index definition, and remove the note about equal relations (= and IN)
being the only supported operations. Vector search filtering currently
supports WHERE clauses on primary key columns only.
Closesscylladb/scylladb#28949
This PR adds integrity verification for SSTable component files during loading. When component digests are present in Scylla metadata, the loader now validates each component's CRC32 digest against the stored expected value, catching silent corruption of component files. Index, Rows and Partitions components digests are also validated duriung scrub in validate mode
Added corruption tests that write an SSTable, flip a bit in a specific component file, then verify that reloading the SSTable detects the corruption and throws the expected exception.
Depends on https://github.com/scylladb/scylladb/pull/28338
Backport is not required, this is new feature
Fixes https://github.com/scylladb/scylladb/issues/20103Closesscylladb/scylladb#28761
* github.com:scylladb/scylladb:
test/cqlpy: test --ignore-component-digest-mismatch flag in scylla sstable upgrade
docs: document --ignore-component-digest-mismatch flag for scylla sstable upgrade
sstables: propagate ignore_component_digest_mismatch config to all load sites
sstables: add option to ignore component digest mismatches
sstable_compaction_test: Add scrub validate test for corrupted index
sstables: add tests for component digest validation on corrupted SSTables
sstables: validate index components digests during SSTable scrub in validate mode
sstables: verify component digests on SSTable load
sstables: add digest_file_random_access_reader for CRC32 digest computation
Document how to migrate a ScyllaDB cluster to different instance
types using the add-and-replace node cycling approach.
Closes: QAINFRA-42
Closesscylladb/scylladb#28458
This pull request adds support for calculation and storing CRC32 digests for all SSTable components.
This change replaces plain file_writer with crc32_digest_file_writer for all SSTable components that should be checksummed. The resulting component digests are stored in the sstable structure
and later persisted to disk as part of the Scylla metadata component during writer::consume_end_of_stream.
Several test cases where introduced to verify expected behaviour.
Additionally, this PR adds new rewrite component mechanism for safe sstable component rewriting.
Previously, rewriting an sstable component (e.g., via rewrite_statistics) created a temporary file that was renamed to the final name after sealing. This allowed crash recovery by simply removing the temporary file on startup.
However, with component digests stored in scylla_metadata (#20100),
replacing a component like Statistics requires atomically updating both the component
and scylla_metadata with the new digest - impossible with POSIX rename.
The new mechanism creates a clone sstable with a fresh generation:
- Hard-links all components from the source except the component being rewritten and scylla_metadata
- Copies original sstable components pointer and recognized components from the source
- Invokes a modifier callback to adjust the new sstable before rewriting
- Writes the modified component along with updated scylla_metadata containing the new digest
- Seals the new sstable with a temporary TOC
- Replaces the old sstable atomically, the same way as it is done in compaction
This is built on the rewrite_sstables compaction framework to support batch operations (e.g., following incremental repair).
In case of any failure durning the whole process, sstable will be automatically deleted on the node startup due to
temporary toc persistence.
Backport is not required, it is a new feature
Fixes https://github.com/scylladb/scylladb/issues/20100, https://github.com/scylladb/scylladb/issues/27453Closesscylladb/scylladb#28338
* github.com:scylladb/scylladb:
docs: document components_digests subcomponent and trailing digest in Scylla.db
sstable_compaction_test: Add tests for perform_component_rewrite
sstable_test: add verification testcases of SSTable components digests persistance
sstables: store digest of all sstable components in scylla metadata
sstables: replace rewrite_statistics with new rewrite component mechanism
sstables: add new rewrite component mechanism for safe sstable component rewriting
compaction: add compaction_group_view method to specify sstable version
sstables: add null_data_sink and serialized_checksum for checksum-only calculation
sstables: extract default write open flags into a constant
sstables: Add write_simple_with_digest for component checksumming
sstables: Extract file writer closing logic into separate methods
sstables: Implement CRC32 digest-only writer
Mention that role and permission changes are durable but may
not be immediately visible on other nodes due to asynchronous
replication.
Fixes: SCYLLADB-651
Closesscylladb/scylladb#28900
Document the new `components_digests` subcomponent (tag 12) added to the
Scylla.db metadata component, which stores CRC32 digests of all checksummed
SSTable component files. Also document the trailing CRC32 digest that
stores digest of the scylla metadata itself.
This commit updates the documentation for the unified installer.
- The Open Source example is replaced with version 2025.1 (Source Available, currently supported, LTS).
- The info about CentOS 7 is removed (no longer supported).
- Java 8 is removed.
- The example for cassandra-stress is removed (as it was already removed on other installation pages).
Fixes https://github.com/scylladb/scylladb/issues/28150Closesscylladb/scylladb#28152
Currently, repair-mode tombstone-gc cannot be used on tables with RF=1. We want to make repair-mode the default for all tablet tables (and more, see https://github.com/scylladb/scylladb/issues/22814), but currently a keyspace created with RF=1 and later altered to RF>1 will end up using timeout-mode tombstone gc. This is because the repair-mode tombstone-gc code relies on repair history to determine the gc-before time for keys/ranges. RF=1 tables cannot run repairs so they will have empty repair history and consequently won't be able to purge tombstones.
This PR solves this by keeping a registry of RF=1 tables and consulting this registry when creating `tombstone_gc_state` objects. If the table is RF=1, tombstone-gc will work as if the table used immediate-mode tombstone-gc. The registry is updated on each replication update. As soon as the table is not RF=1 anymore, the tombstone-gc reverts to the natural repair-mode behaviour.
After this PR, tombstone-gc defaults to repair-mode for all tables, regardless of RF and tablets/vnodes.
Fixes: SCYLLADB-106.
New feature, no backport required.
Closesscylladb/scylladb#22945
* github.com:scylladb/scylladb:
test/{boost,cluster}: add test for tombstone gc mode=repair with RF=1
tombstone_gc: allow use of repair-mode for RF=1 tables
replica/table: update rf=1 table registry in shared tombstone-gc state
tombstone_gc: tombstone_gc_before_getter: consider RF when getting gc before time
tombstone_gc: unpack per_table_history_maps
tombstone_gc: extract _group0_gc_time from per_table_history_map
tombstone_gc: drop tombstone_gc_state(nullptr) ctor and operator bool()
test/lib/random_schema: use timeout-mode tombstone_gc
tombstone_gc_options: add C++ friendly constructor
test: move away from tombstone_gc_state(nullptr) ctor
treewide: move away from tombstone_gc_state(nullptr) ctor
sstable: move away from tombstone_gc_mode::operator bool()
replica/table: add get_tombstone_gc_state()
compaction: use tombstone_gc_state with value semantics
db/row_cache: use tombstone_gc_state with value semantics
tombstone_gc: introduce tombstone_gc_state::for_tests()
This patch series removes creation of default 'cassandra:cassandra' superuser on system start.
Disable creation of a superuser with default 'cassandra:cassandra' credentials to improve security. The current flow requires clients to create another superuser and then drop the default `cassandra:cassandra' role. For those who do, there is a time window where the default credentials exist. For those who do not, that role stays. We want to improve security by forcing the client to either use config to specify default values for default superuser name and password or use cqlsh over maintenance socket connection to explicitly create/alter a superuser role.
The patch series:
- Enable role modification over the maintenance socket
- Stop using default 'cassandra' value for default superuser, skipping creation instead
Design document: https://scylladb.atlassian.net/wiki/spaces/RND/pages/165773327/Drop+default+cassandra+superuserFixesscylladb/scylla-enterprise#5657
This is an improvement. It does not need a backport.
Closesscylladb/scylladb#27215
* github.com:scylladb/scylladb:
config: enable maintenance socket in workdir by default
docs: auth: do not specify password with -p option
docs: update documentation related to default superuser
test: maintenance socket role management
test: cluster: add logs to test_maintenance_socket.py
test: pylib: fix connect_driver handling when adding and starting server
auth: do not create default 'cassandra:cassandra' superuser
auth: remove redundant DEFAULT_USER_NAME from password authenticator
auth: enable role management operations via maintenance socket
client_state: add has_superuser method
client_state: add _bypass_auth_checks flag
auth: let maintenance_socket_role_manager know if node is in maintenance mode
auth: remove class registrator usage
auth: instantiate auth service with factory functors
auth: add service constructor with factory functors
auth: add transitional.hh file
service: qos: handle special scheduling group case for maintenance socket
service: qos: use _auth_integration as condition for using _auth_integration
Modify the methods which calculate the default gc mode as well as that
which validates whether repair-mode can be used at all, so both accepts
use of repair-mode on RF=1 tables.
This de-facto changes the default tombstone-gc to repair-mode for all
tables. Documentation is updated accordingly.
Some tests need adjusting:
* cqlpy/test_select_from_mutation_fragments.py: disable GC for some test
cases because this patch makes tombstones they write subject to GC
when using defaults.
* test/cluster/test_mv.py::test_mv_tombstone_gc_not_inherited used
repair-mode as a non-default for the base table and expected the MV to
revert to default. Another mode has to be used as the non-default
(immediate).
* test/cqlpy/test_tools.py::test_scylla_sstable_dump_schema: don't
compare tombstone_gc schema extension when comparing dumped schema vs.
original. The tool's schema loader doesn't have access to the keyspace
definition so it will come up with different defaults for
tombstone-gc.
* test/boost/row_cache_test.cc::test_populating_cache_with_expired_and_nonexpired_tombstones
sets tombstone expiry assuming the tombstone-gc timeout-mode default.
Change the CREATE TABLE statement to set the expected mode.
In this series we introduce new system tables and use them for storing the raft metadata
for strongly consistent tables. In contrast to the previously used raft group0 tables, the
new tables can store data on any shard. The tables also allow specifying the shard where
each partition should reside, which enables the tablets of strongly consistent tables to have
their raft group metadata co-located on the same shard as the tablet replica.
The new tables have almost the same schemas as the raft group0 tables. However, they
have an additional column in their partition keys. The additional column is the shard
that specifies where the data should be located. While a tablet and its corresponding
raft group server resides on some shard, it now writes and reads all requests to the
metadata tables using its shard in addition to the group_id.
The extra partition key column is used by the new partitioner and sharder which allow
this special shard routing. The partitioner encodes the shard in the token and the
sharder decodes the shard from the token. This approach for routing avoids any
additional lookups (for the tablet mapping) during operations on the new tables
and it also doesn't require keeping any state. It also doesn't interact negatively
with resharding - as long as tablets (and their corresponding raft metadata) occupy
some shard, we do not allow starting the node with a shard count lower than the
id of this shard. When increasing the shard count, the routing does not change,
similarly to how tablet allocation doesn't change.
To use the new tables, a new implementation of `raft::persistence` is added. Currently,
it's almost an exact copy of the `raft_sys_table_storage` which just uses the new tables,
but in the future we can modify it with changes specific to metadata (or mutation)
storage for strongly consistent tables. The new storage is used in the `groups_manager`,
which combined with the removal of some `this_shard_id() == 0` checks, allows strongly
consistent tables to be used on all shards.
This approach for making sure that the reads/writes to the new tables end up on the correct shards
won in the balance of complexity/usability/performance against a few other approaches we've considered.
They include:
1. Making the Raft server read/write directly to the database, skipping the sharder, on its shard, while using
the default partitioner/sharder. This approach could let us avoid changing the schema and there should be
no problems for reads and writes performed by the Raft server. However, in this approach we would input
data in tables conflicting with the placement determined by the sharder. As a result, any read going through
the sharder could miss the rows it was supposed to read. Even when reading all shards to find a specific value,
there is a risk of polluting the cache - the rows loaded on incorrect shards may persist in the cache for an unknown
amount of time. The cache may also mistakenly remember that a row is missing, even though it's actually present,
just on an incorrect shard.
Some of the issues with this approach could be worked around using another sharder which always returns
this_shard_id() when asked about a shard. It's not clear how such a sharder would implement a method like
`token_for_next_shard`, and how much simpler it would be compared to the current "identity" sharder.
2. Using a sharder depending on the current allocation of tablets on the node. This approach relies on the
knowledge of group_id -> shard mapping at any point in time in the cluster. For this approach we'd also
need to either add a custom partitioner which encodes the group_id in the token, or we'd need to track the
token(group_id) -> shard mapping. This approach has the benefit over the one used in the series of keeping
the partition key as just group_id. However, it requires more logic, and the access to the live state of the node
in the sharder, and it's not static - the same token may be sharded differently depending on the state of the
node - it shouldn't occur in practice, but if we changed the state of the node before adjusting the table data,
we would be unable to access/fix the stale data without artificially also changing the state of the node.
3. Using metadata tables co-located to the strongly consistent tables. This approach could simplify the
metadata migrations in the future, however it would require additional schema management of all co-located
metadata tables, and it's not even obvious what could be used as the partition key in these tables - some
metadata is per-raft-group, so we couldn't reuse the partition key of the strongly consistent table for it. And
finding and remembering a partition key that is routed to a specific shard is not a simple task. Finally, splits
and merges will most likely need special handling for metadata anyway, so we wouldn't even make use of
co-located table's splits and merges.
Fixes [SCYLLADB-361](https://scylladb.atlassian.net/browse/SCYLLADB-361)
[SCYLLADB-361]: https://scylladb.atlassian.net/browse/SCYLLADB-361?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQClosesscylladb/scylladb#28509
* github.com:scylladb/scylladb:
docs: add strong consistency doc
test/cluster: add tests for strongly-consistent tables' metadata persistence
raft: enable multi-shard raft groups for strongly consistent tablets
test/raft: add unit tests for raft_groups_storage
raft: add raft_groups_storage persistence class
db: add system tables for strongly consistent tables' raft groups
dht: add fixed_shard_partitioner and fixed_shard_sharder
raft: add group_id -> shard mapping to raft_group_registry
schema: add with_sharder overload accepting static_sharder reference
Fixes issue #12818 with the following docs changes:
docs/dev/system_keyspace.md: Added missing system tables, added table of contents (TOC), added categories
Closesscylladb/scylladb#27789
Specifying password with -p option is considered unsafe.
The password will be saved in bash history.
The preferred approach is to enter the password when prompted.
Any approach that passes the password via command line arguments
makes that password visible in process options (ps command), no matter
if the password is passed directly or as an environment variable.
Refs SCYLLADB-409
Update create superuser procedure:
- Remove notes about default `cassandra` superuser
- Add create superuser using existing superuser section
- Update create superuser by using `scylla.yaml` config
- Add create superuser using maintenance socket
Update password reset procedure:
- Add maintenance socket approach
- Remove the old approach with deleting all the roles
Update enabling authentication with downtime and during runtime:
- Mention creating new superuser over the maintenance socket
- Remove default superuser usage
Update enable authorization:
- Mention creating new superuser over the maintenance socket
- Remove mention of default superuser
Reasoning for deletion of the old approach:
- [old] Needs cluster downtime, removes all roles, needs recreation of roles,
needs maintenance socket anyways, if config values are not used for superuser
- [new] No cluster downtime, possibly one node restart to enable maintenance
socket, faster
Refs SCYLLADB-409
Introduced a new max_tablet_count tablet option that caps the maximum number of tablets a table can have. This feature is designed primarily for backup and restore workflows.
During backup, when load balancing is disabled for snapshot consistency, the current tablet count is recorded in the backup manifest.
During restore, max_tablet_count is set to this recorded value, ensuring the restored table's tablet count never exceeds the original snapshot's tablet distribution.
This guarantee enables efficient file-based SSTable streaming during restore, as each SSTable remains fully contained within a single tablet boundary.
Closesscylladb/scylladb#28450
