Commit Graph

479 Commits

Author SHA1 Message Date
Botond Dénes
3158e9b017 doc: reorganize properties in config.cc and config.hh
This commit moves the "Ungrouped properties" category to the end of the
properties list. The properties are now published in the documentation,
and it doesn't look good if the list starts with ungrouped properties.

This patch was taken over from Anna Stuchlik <anna.stuchlik@scylladb.com>.

Closes scylladb/scylladb#28343
2026-01-29 11:27:42 +03:00
Łukasz Paszkowski
21348050e8 config: Add parameters to control reads' preemptive_abort_factor 2026-01-28 14:20:01 +01:00
Botond Dénes
7d2e6c0170 Merge 'config: add enforce_rack_list option' from Aleksandra Martyniuk
Add enforce_rack_list option. When the option is set to true,
all tablet keyspaces have rack list replication factor.

When the option is on:
- CREATE STATEMENT always auto-extends rf to rack lists;
- ALTER STATEMENT fails when there is numeric rf in any DC.

The flag is set to false by default and a node needs to be restarted
in order to change its value. Starting a node with enforce_rack_list
option will fail, if there are any tablet keyspaces with numeric rf
in any DC.

enforce_rack_list is a per-node option and a user needs to ensure
that no tablet keyspace is altered or created while nodes in
the cluster don't have the consistent value.

Mark rf_rack_valid_keyspaces as deprecated.

Fixes: https://github.com/scylladb/scylladb/issues/26399.

New feature; no backport needed

Closes scylladb/scylladb#28084

* github.com:scylladb/scylladb:
  test: add test for enforce_rack_list option
  db: mark rf_rack_valid_keyspaces as deprecated
  config: add enforce_rack_list option
  Revert "alternator: require rf_rack_valid_keyspaces when creating index"
2026-01-22 10:27:35 +02:00
Aleksandra Martyniuk
7dc371f312 db: mark rf_rack_valid_keyspaces as deprecated
Mark rf_rack_valid_keyspaces option as deprecated. User should
use enforce_rack_list option instead.

The option can still be used and it does not change it's behavior.

Docs is updated accordingly.
2026-01-20 09:58:57 +01:00
Aleksandra Martyniuk
761ace4f05 config: add enforce_rack_list option
Add enforce_rack_list option. When the option is set to true,
all tablet keyspaces have rack list replication factor.

When the option is on:
- CREATE STATEMENT always auto-extends rf to rack lists;
- ALTER STATEMENT fails when there is numeric rf in any DC.

The flag is set to false by default and a node needs to be restarted
in order to change its value. Starting a node with enforce_rack_list
option will fail, if there are any tablet keyspaces with numeric rf
in any DC.

enforce_rack_list is a per-node option and a user needs to ensure
that no tablet keyspace is altered or created while nodes in
the cluster don't have the consistent value.
2026-01-20 09:58:51 +01:00
Nikos Dragazis
7fa1f87355 db/config: Update sstable_compression_user_table_options description
Clarify what "user table" means.

Signed-off-by: Nikos Dragazis <nikolaos.dragazis@scylladb.com>
2026-01-13 20:45:59 +02:00
Nikos Dragazis
76b2d0f961 db: config: Add accessor for sstable_compression_user_table_options
The `sstable_compression_user_table_options` config option determines
the default compression settings for user tables.

In patch 2fc812a1b9, the default value of this option was changed from
LZ4 to LZ4WithDicts and a fallback logic was introduced during startup
to temporarily revert the option to LZ4 until the dictionary compression
feature is enabled.

Replace this fallback logic with an accessor that returns the correct
settings depending on the feature flag. This is cleaner and more
consistent with the way we handle the `sstable_format` option, where the
same problem appears (see `get_preferred_sstable_version()`).

As a consequence, the configuration option must always be accessed
through this accessor. Add a comment to point this out.

Signed-off-by: Nikos Dragazis <nikolaos.dragazis@scylladb.com>
2026-01-13 18:30:38 +02:00
Avi Kivity
66aee0fb5e alternator: add optional listeners for proxy protocol v2
Following 954f2cbd2f, which added proxy protocol v2 listeners
for CQL, we do the same for alternator. We add two optional ports
for plain and TLS-wrapped HTTP.

We test each new port, that the old ports still work, and that
mixing up a port with no proxy protocol and a connection with proxy
protocol (or the opposite) fails. The latter serves to show
that the testing strategy is valid and doesn't just pass whatever
happens. We also verify that the correct addresses (and TLS mode)
show up in system.clients.

Closes scylladb/scylladb#27889
2026-01-13 09:59:24 +02:00
Asias He
7ba7b25bdd repair: Implement auto repair for tablet repair
This patch implements the basic auto repair support for tablet repair.

It was decided to add no per table configuration for the initial
implementation, so two scylla yaml config options are introduced to set
the default auto repair configs for all the tablet tables.

- auto_repair_enabled_default

Set true to enable auto repair for tablet tables by default. The value
will be overridden by the per keyspace or per table configuration which
is not implemented yet.

- auto_repair_threshold_default_in_seconds

Set the default time in seconds for the auto repair threshold for tablet
tables. If the time since last repair is bigger than the configured
time, the tablet is eligible for auto repair. The value will be
overridden by the per keyspace or per table configuration which is not
implemented yet.

The following metrcis are added:

- auto_repair_needs_repair_nr

The number of tablets with auto repair enabled that needs repair

- auto_repair_enabled_nr

The number of tablets with auto repair enabled

The metrics are useful to tell if auto repair is falling behind.

In the future, more auto repair scheduling will be added, e.g.,
scheduling based on the repaired and unrepaired sstable set size,
tombstone ratio and so on, in addition to the time based scheduling.

Fixes SCYLLADB-99
2026-01-09 16:11:39 +08:00
Szymon Malewski
ec329f85b0 alternator/http_compression: Add handling of Accept-Encoding header
This is an initial patch to add support of Alternator's compressed responses.
The actual compression (gzip,deflate) will be added in the following commits.
The main functionality added in this commmit is parsing of Accept-Encoding header,
that indicates compression algorithms supported by the client.
In this commit we add also configuration parameters of response gzip/deflate compression.
They allow to enable/disable compression, set level and a size threshold below which a response is not compressed.
With current implementation it is possible to decide a compression for each response, but it is not used yet.
2026-01-05 10:14:40 +01:00
Tomasz Grabiec
bbf9ce18ef Merge 'load_balancer: compute node load based on tablet sizes' from Ferenc Szili
Currently, the tablet load balancer performs capacity based balancing by collecting the gross disk capacity of the nodes, and computes balance assuming that all tablet sizes are the same.

This change introduces size-based load balancing. The load balancer does not assume identical tablet sizes any more, and computes load based on actual tablet sizes.

The size-based load balancer computes the difference between the most and least loaded nodes in the balancing set (nodes in DC, or nodes in a rack in case of `rf-rack-valid-keyspaces`) and stops further balancing if this difference is bellow the config option `size_based_balance_threshold_percentage`.

This config option does not apply to the absolute load, but instead to the percentage of how much the most loaded node is more loaded than the least loaded node:

`delta = (most_loaded - least_loaded) / most_loaded`

If this delta is smaller then the config threshold, the balancer will consider the nodes balanced.

This PR is a part of a series of PRs which are based on top of each other.

- First part for tablet size collection via load_stats: #26035
- Second part reconcile load_stats: #26152
- The third part for load_sketch changes: #26153
- The fourth part which performs tablet load balancing based on tablet size: #26254
- The fifth part changes the load balancing simulator: #26438

This is a new feature, backport is not needed.

Fixes #26254

Closes scylladb/scylladb#26254

* github.com:scylladb/scylladb:
  test, load balancing: add test for table balance
  load_balancer: add cluster feature for size based balancing
  load_balancer: implement size-based load balancing
  config: add size based load balancing config params
  load_stats: use trinfo to decide how to reconcile tablet size
  load_sketch: use tablet sizes in load computation
  load_stats: add get_tablet_size_in_transition()
2025-12-29 15:01:38 +01:00
Radosław Cybulski
a532fc73bc Add alternator_describe_table_info_cache_validity_in_seconds config option
Add a `alternator_describe_table_info_cache_validity_in_seconds`
configuration option with default value of 6 hours.
2025-12-29 08:33:05 +01:00
Ferenc Szili
cc9e125f12 config: add size based load balancing config params
This change adds:

- The config paremeter force_capacity_based_balancing which, when
  enabled performs capacity based balancing instead of size based.
- The config parameter size_based_balance_threshold_percentage which
  sets the balance threshold for the size based load balancer.
- The config parameter minimal_tablet_size_for_balancing which sets the
  minimal tablet size for the load balancer.
2025-12-27 10:37:38 +01:00
Avi Kivity
1382b47d45 config, transport: support proxy protocol v2 enhanced connections
We have four native transport ports: two for plain/TLS, and two
more for shard-aware (plain/TLS as well). Add four more that expect
the proxy protocol v2 header. This allows nodes behind a reverse
proxy to record the correct source address and port in system.clients,
and the shard-aware port to see the correct source port selection
made my the client.
2025-12-17 14:18:04 +02:00
Pavel Emelyanov
3f7ee3ce5d Merge 'batchlog: make replay (flush) faster' from Botond Dénes
The batchlog table contains an entry for each logged batch that is processed by the local node as coordinator. These entries are typically very short lived, they are inserted when the batch is processed and deleted immediately after the batch is successfully applied.
When a table has `tombstone_gc = {'mode': 'repair'}` enabled, every repair has to flush all hints and batchlogs, so that we can be certain that there is no live data in any of these, older than the last repair. Since batches can contain member queries from any number of tables, the whole batchlog has to be flushed, even if repair-mode tombstone-gc is enabled for a single table.

Flushing the batchlog table happens by doing a batchlog replay. This involves reading the entire content of this table, and attempting to replay+delete any live entries (that are old enough to be replayed).  Under normal operating circumstances, 99%+ of the content of the batchlog table is partition tombstones.  Because of this, scanning the content of this table has to process thousands to millions of tombstones. This was observed to require up to 20 minutes to finish, causing repairs to slow down to a crawl, as the batchlog-flush has to be repeated at the end of the repair of each token-range.

When trying to address this problem, the first idea was that we should expedite the garbage-collection of these accumulated tombstones. This experiment failed, see https://github.com/scylladb/scylladb/pull/23752. The commitlog proved to be an impossible to bypass barrier, preventing quick garbage-collection of tombstones. So long as a single commit-log segment is alive, holding content from the batchlog table, all tombstones written after are blocked from GC.
The second approach, represented by this PR, is to not rely in tombstone GC to reduce the tombstone amount. Instead restructure the table such that a single higher-order tombstone can be used to shadow and allow for the eviction of the myriads of individual batchlog entry tombstones. This is realized by reorganizing the batchlog table such that individual batches are rows, not partitions.
This new schema is introduced by the new `system.batchlog_v2` table, introduced by this PR:

    CREATE TABLE system.batchlog_v2 (
        version int,
        stage int,
        shard int,
        written_at timestamp,
        id uuid,
        data blob,
        PRIMARY KEY ((version, stage, shard), written_at, id));

The new schema organization has the following goals:
1) Make post-replay batchlog cleanup possible with a simple range-tombstone. This allows dropping the individual dead batchlog entries, as they are shadowed by a higher level tombstone. This enables dropping tombstones without tombstone GC.
2) To make the above possible, introduce the stage key component: batchlog entries that fail the first replay attempt, are moved to the failed_replay stage, so the initial stage can be cleaned up safely.
3) Spread out the data among Scylla shards, via the batchlog shard column.
4) Make batchlog entries ordered by the batchlog create time (id). This allows for selecting batchlogs to replay, without post-filtering of batchlogs that are too young to be replayed.

Fixes: https://github.com/scylladb/scylladb/issues/23358

This is an improvement, normally not a backport-candidate. We might override this and backport to allow wider use of `tombstone_gc: {'mode': 'repair'}`.

Closes scylladb/scylladb#26671

* github.com:scylladb/scylladb:
  db/config: change batchlog_replay_cleanup_after_replays default to 1
  test/boost/batchlog_manager_test: add test for batchlog cleanup
  replica/mutation_dump: always set position weight for clustering positions
  service/storage_proxy: s/batch_replay_throw/storage_proxy_fail_replay_batch/
  test/lib: introduce error_injection.hh
  utils/error_injection: add debug log to disable() and disable_all()
  test/lib/cql_test_env: forward config to batchlog
  test/lib/cql_test_env: add batch type to execute_batch()
  test/lib/cql_assertions: add with_size(predicate) overload
  test/lib/cql_assertions: add source location to fail messages
  test/lib/cql_assertions: columns_assertions: add assert_for_columns_of_each_row()
  test/lib/cql_assertions: rows_assertions::assert_for_columns_of_row(): add index bound check
  test/lib/cql_assertions: columns_assertions: add T* with_typed_column() overload
  db/batchlog_manager: config: s/write_timeout/reply_timeot/
  db,service: switch to system.batchlog_v2
  db/system_keyspace: introduce system.batchlog_v2
  service,db: extract generation of batchlog delete mutation
  service,db: extract get_batchlog_mutation_for() from storage-proxy
  db/batchlog_manager: only consider propagation delay with tombstone-gc=repair
  db/batchlog_manager: don't drop entire batch if one mutations' table was dropped
  data_dictionary: table: add get_truncation_time()
  db/batchlog_manager: batch(): replace map_reduce() with simple loop
  db/batchlog_manager: finish coroutinizing replay_all_failed_batches
  db/batchlog_manager: improve replayAllFailedBatches logs
2025-12-15 15:05:19 +03:00
Szymon Wasik
4f803aad22 Improve documentation of vector search configuration parameters.
This patch adds separate group for vector search parameters in the
documentation and fixes small typos and formatting.

Fixes: SCYLLADB-77.

Closes scylladb/scylladb#27385
2025-12-03 21:02:59 +02:00
Botond Dénes
e762027943 db/config: change batchlog_replay_cleanup_after_replays default to 1
Now that batchlog cleanup is cheap, on account of memtable flush on the
system.batchlog table garbage-collecting tombstones (previous patch), we
can afford to do cleanup on each replay, keeping the memtable size small
and more importantly -- the amount of tombstones in the memtable small.
2025-12-02 14:21:26 +02:00
Piotr Dulikowski
44c605e59c Merge 'Fix the types of change events in Alternator Streams' from Piotr Wieczorek
This patch increases the compatibility with DynamoDB Streams by integrating the DynamoDB's event type rules (described in https://github.com/scylladb/scylladb/issues/6918) into Alternator. The main changes are:
- introduce a new flag `alternator_streams_strict_compatibility`, meant as a guard of performance-intensive operations that increase the compatibility with DynamoDB Streams. If enabled, Alternator always performs a RBW before a data-modifying operation, and propagates its result to CDC. Then, the old item is compared to the new one, to determine the mutation type (INSERT vs MODIFY). This option is a no-op for tables with disabled Alternator Streams,
- reduce splitting of simple Alternator mutations,
- correctly distinguish event types described in #6918, except for item deletes. Deleting a missing item with DeleteItem, BatchWriteItem, or a missing field with UpdateItem still emit REMOVEs.

To summarize, the emitted events of the data manipulation operations should be as follows:
- DeleteItem/BatchWriteItem.DeleteItem of existing item: REMOVE (OK)
- DeleteItem of nonexistent item: nothing (OK)
- BatchWriteItem.DeleteItem of nonexistent item: nothing (OK)
- PutItem/UpdateItem/BatchWriteItem.PutItem of existing and not equal item: MODIFY (OK)
- PutItem/UpdateItem/BatchWriteItem.PutItem of existing and equal item: nothing (OK)
- PutItem/UpdateItem/BatchWriteItem.PutItem of nonexistent item: INSERT (OK)

No backport is necessary.

Refs https://github.com/scylladb/scylladb/pull/26149
Refs https://github.com/scylladb/scylladb/pull/26396
Refs https://github.com/scylladb/scylladb/issues/26382
Fixes https://github.com/scylladb/scylladb/issues/6918

Closes scylladb/scylladb#26121

* github.com:scylladb/scylladb:
  test/alternator: Enable the tests failing because of #6918
  alternator, cdc: Don't emit events for no-op removes
  alternator, cdc: Don't emit an event for equal items
  alternator/streams, cdc: Differentiate item replace and item update in CDC
  alternator: Change the return type of rmw_operation_return
  config: Add alternator_streams_strict_compatibility flag
  cdc: Don't split a row marker away from row cells
2025-11-30 07:20:22 +01:00
Botond Dénes
384bffb8da Merge 'compaction: limit the maximum shares allocated to a compaction scheduling class' from Raphael Raph Carvalho
This PR adds support for limiting the maximum shares allocated to a
compaction scheduling class by the compaction controller. It introduces
a new configuration parameter, compaction_max_shares, which, when set
to a non zero value, will cap the shares allocated to compaction jobs.
This PR also exposes the shares computed by the compaction controller
via metrics, for observability purposes.

Fixes https://github.com/scylladb/scylladb/issues/9431

Enhancement. No need to backport.

NOTE: Replaces PR https://github.com/scylladb/scylladb/pull/26696

Ran a test in which the backlog raised the need for max shares (normalized backlog above normalization_factor), and played with different values for new option compaction_max_shares to see it works (500, 1000, 2000, 250, 50)

Closes scylladb/scylladb#27024

* github.com:scylladb/scylladb:
  db/config: introduce new config parameter `compaction_max_shares`
  compaction_manager:config: introduce max_shares
  compaction_controller: add configurable maximum shares
  compaction_controller: introduce `set_max_shares()`
2025-11-26 06:51:30 +02:00
Lakshmi Narayanan Sreethar
9cb766f929 db/config: introduce new config parameter compaction_max_shares
Add support for the new configuration parameter `compaction_max_shares`,
and update the compaction manager to pass it down to the compaction
controller when it changes. The shares allocated to compaction jobs will
be limited by this new parameter.

Fixes #9431

Signed-off-by: Lakshmi Narayanan Sreethar <lakshmi.sreethar@scylladb.com>
2025-11-24 12:52:29 -03:00
Karol Nowacki
c40b3ba4b3 vector_search: Add HTTPS support for vector store connections
This commit introduces TLS encryption support for vector store connections.
A new configuration option is added:
- vector_store_encryption_options.truststore: path to the trust store file

To enable secure connections, use the https:// scheme in the
vector_store_primary_uri/vector_store_secondary_uri configuration options.

Fixes: VECTOR-327
2025-11-22 08:18:45 +01:00
Calle Wilund
3c4546d839 messaging_service: Add internode_compression=rack as option
Fixes #27085

Adds a "rack" option to enum/config and handles in connection
setup in messaging_service.

Closes scylladb/scylladb#27099
2025-11-21 11:50:55 +02:00
Karol Nowacki
104de44a8d vector_search: Add support for secondary vector store clients
This change adds support for secondary vector store clients, typically
located in different availability zones. Secondary clients serve as
fallback targets when all primary clients are unavailable.
New configuration option allows specifying secondary client addresses
and ports.

Fixes: VECTOR-187

Closes scylladb/scylladb#26484
2025-11-20 08:37:18 +01:00
Botond Dénes
2ca66133a4 Revert "db/config: don't use RBNO for scaling"
This reverts commit 43738298be.

This commit causes instability in dtests. Several non-gating dtests
started failing, as well as some gating ones, see #27047.

Closes scylladb/scylladb#27067

Fixes #27047
2025-11-18 08:17:17 +02:00
Botond Dénes
43738298be db/config: don't use RBNO for scaling
Remove bootstrap and decomission from allowed_repair_based_node_ops.
Using RBNO over streaming for these operations has no benefits, as they
are not exposed to the out-of-date replica problem that replace,
removenode and rebuild are.
On top of that, RBNO is known to have problems with empty user tables.
Using streaming for boostrap and decomission is safe and faster
than RBNO in all condition, especially when the table is small.

One test needs adjustment as it relies on RBNO being used for all node
ops.

Fixes: #24664

Closes scylladb/scylladb#26330
2025-11-14 13:03:50 +03:00
Nadav Har'El
25439127c8 config: make tablets_mode_for_new_keyspaces live-updatable
We have a configuration option "tablets_mode_for_new_keyspaces" which
determines whether new keyspaces should use tablets or vnodes.

For some reason, this configuration parameter was never marked live-
updatable, so in this patch we add flag. No other changes are needed -
the existing code that uses this flag always uses it through the
up-to-date configuration.

In the previous patches we start to honor tablets_mode_for_new_keyspaces
also in Alternator CreateTable, and we wanted to test this but couldn't
do this in test/alternator because the option was not live-updatable.
Now that it will be, we'll be able to test this feature in
test/alternator.

Signed-off-by: Nadav Har'El <nyh@scylladb.com>
2025-11-09 12:52:29 +02:00
Piotr Szymaniak
af00b59930 Fix incorrect hint for tablets_mode_for_new_keyspaces 2025-11-09 10:49:46 +02:00
Pavel Emelyanov
59019bc9a9 Merge 'Alternator: allow warning on auth errors before enabling enforcement' from Nadav Har'El
An Alternator user was recently "bit" when switching `alternator_enforce_authorization` from "false" to "true": ְְְAfter the configuration change, all application requests suddenly failed because unbeknownst to the user, their application used incorrect secret keys.

This series introduces a solution for users who want to **safely** switch `alternator_enforce_authorization`  from "false" to "true": Before switching from "false" to "true", the user can temporarily switch a new option, `alternator_warn_authorization`, to true. In this "warn" mode, authentication and authorization errors are counted in metrics (`scylla_alternator_authentication_failures` and `scylla_alternator_authorization_failures`) and logged as WARNings, but the user's application continues to work. The user can use these metrics or log messages to learn of errors in their application's setup, fix them, and only do the switch of `alternator_enforce_authorization` when the metrics or log messages show there are no more errors.

The first patch is the implementation of the the feature - the new configuration option, the metrics and the log messages,  the second patch is a test for the new feature, and the third patch is documentation recommending how to use the warn mode and the associated metrics or log messages to safely switch `alternaor_enforce_authorization` from false to true.

Fixes #25308

This is a feature that users need, so it should probably be backported to live branches.

Closes scylladb/scylladb#25457

* github.com:scylladb/scylladb:
  docs/alternator: explain alternator_warn_authorization
  test/alternator: tests for new auth failure metrics and log messages
  alternator: add alternator_warn_authorization config
2025-11-05 10:45:17 +03:00
Nikos Dragazis
2fc812a1b9 db/config: Change default SSTable compressor to LZ4WithDictsCompressor
`sstable_compression_user_table_options` allows configuring a
node-global SSTable compression algorithm for user tables via
scylla.yaml. The current default is `LZ4Compressor` (inherited from
Cassandra).

Make `LZ4WithDictsCompressor` the new default. Metrics from real datasets
in the field have shown significant improvements in compression ratios.

If the dictionary compression feature is not enabled in the cluster
(e.g., during an upgrade), fall back to the `LZ4Compressor`. Once the
feature is enabled, flip the default back to the dictionary compressor
using with a listener callback.

Signed-off-by: Nikos Dragazis <nikolaos.dragazis@scylladb.com>
2025-10-30 15:53:49 +02:00
Piotr Wieczorek
ffdc8d49c7 config: Add alternator_streams_strict_compatibility flag
With this flag enabled, Alternator Streams produces more accurate event
types:
- nop operations (i.e. replacing an item with an identical one, deleting
  a nonexistent item) don't produce an event,
- updates of an existing item produce a MODIFY event, instead of INSERT,
- etc.

This flag affects the internal behaviour of some operations, i.e.
Alternator may select a preimage and propagate it to CDC (in contrary to
CDC making the request), or do extra item comparisons (i.e. compare the
existing item with the new one). These operations may be costly, and
users that don't use Streams won't need them.

This flag is live-updatable. An operation reads this flag once, and uses
its value for the entire operation.
2025-10-30 07:40:31 +01:00
Nikos Dragazis
96e727d7b9 db/config: Deprecate sstable_compression_dictionaries_allow_in_ddl
The option is a knob that allows to reject dictionary-aware compressors
in the validation stage of CREATE/ALTER statements, and in the
validation of `sstable_compression_user_table_options`. It was
introduced in 7d26d3c7cb to allow the admins of Scylla Cloud to
selectively enable it in certain clusters. For more details, check:
https://github.com/scylladb/scylla-enterprise/issues/5435

As of this series, we want to start offering dictionary compression as
the default option in all clusters, i.e., treat it as a generally
available feature. This makes the knob redundant.

Additionally, making dictionary compression the default choice in
`sstable_compression_user_table_options` creates an awkward dependency
with the knob (disabling the knob should cause
`sstable_compression_user_table_options` to fall back to a non-dict
compressor as default). That may not be very clear to the end user.

For these reasons, mark the option as "Deprecated", remove all relevant
tests, and adjust the business logic as if dictionary compression is
always available.

Signed-off-by: Nikos Dragazis <nikolaos.dragazis@scylladb.com>
2025-10-29 20:13:08 +02:00
Nadav Har'El
51186b2f2c alternator: add alternator_warn_authorization config
Before this patch, the configuration alternator_enforce_authorization
is a boolean: true means enforce authentication checks (i.e., each
request is signed by a valid user) and authorization checks (the user
who signed the request is allowed by RBAC to perform this request).

This patch adds a second boolean configuration option,
alternator_warn_authorization. When alternator_enforce_authorization
is false but alternator_warn_authorization is true, authentication and
authorization checks are performed as in enforce mode, but failures
are ignored and counted in two new metrics:

    scylla_alternator_authentication_failures
    scylla_alternator_authorization_failures

additionally,also each authentication or authorization error is logged as
a WARN-level log message. Some users prefer those log messages over
metrics, as the log messages contain additional information about the
failure that can be useful - such as the address of the misconfigured
client, or the username attempted in the request.

All combinations of the two configuration options are allowed:
 * If just "enforce" is true, auth failures cause a request failure.
   The failures are counted, but not logged.
 * If both "enforce" and "warn" are true, auth failures cause a request
   failure. The failures are both counted and logged.
 * If just "warn" is true, auth failures are ignored (the request
   is allowed to compelete) but are counted and logged.
 * If neither "enforce" nor "warn" are true, no authentication or
   authorization check are done at all. So we don't know about failures,
   so naturally we don't count them and don't log them.

This patch is fairly straightforward, doing mainly the following
things:

1. Add an alternator_warn_authorization config parameter.

2. Make sure alternator_enforce_authorization is live-updatable (we'll
   use this in a test in the next patch). It "almost" was, but a typo
   prevented the live update from working properly.

3. Add the two new metrics, and increment them in every type of
   authentication or authorization error.
   Some code that needs to increment these new metrics didn't have
   access to the "stats" object, so we had to pass it around more.

4. Add log messages when alternator_warn_authorization is true.

5. If alternator_enforce_authorization is false, allow the auth check
   to allow the request to proceed (after having counted and/or logged
   the auth error).

A separate patch will follow and add documentation suggesting to users
how to use the new "warn" options to safely switch between non-enforcing
to enforcing mode. Another patch will add tests for the new configuration
options, new metrics and new log messages.

Fixes #25308.

Signed-off-by: Nadav Har'El <nyh@scylladb.com>
2025-10-29 11:16:26 +02:00
Radosław Cybulski
ea6b22f461 Add max trace size output configuration variable
In #24031 users complained, that trace message is truncated, namely it's
no longer json parsable and table name might not be part of the output.
This path enables users to configure maximum size of trace message.
In case user wanted `table` name, but didn't care about message size,
 #26634 will help.

- add configuration varable `alternator_max_users_query_size_in_trace_output`
   with default value of 4096 (4 times old default value).
- modify `truncated_content_view` function to use new configuration
  variable for truncation limit
- update `truncated_content_view` to consistently truncate at given
  size, previously trunctation would also happen when data arrived in
  more than one chunk
- update `truncated_content_view` to better handle truncated value
  (limit number of copies)
- fix `scylla_config_read` call - call to `query` for a configuration
  name that is not existing will return `Items` array empty
  (but present) - this would raise array access exception few lines
  below.
- add test

Refs #26634
Refs #24031

Closes scylladb/scylladb#26618
2025-10-28 13:29:15 +03:00
Pavel Emelyanov
44ed3bbb7c Merge 'RFC: Initial GCP storage backend for scylla (sstables + backup)' from Calle Wilund
Integrates GCP object storage as a working storage backend for scylla sstables as well as backup storage.

Adds an abstraction layer (atm very heavily designed around the s3 client interface and usage) to allow the "storage" etc layers of sstable management to pick transparently between "s3" and "gs" providers.

This modifies the scylla config such that endpoints can optionally (through a "type" param) ref a GS backend.
Similarly with storage_options.

Also adds some IO wrapping primitives to make it more feasible to place some logic at a mid level of the implementation stack (such as making networked storage files, ranged reading etc).

Test s3 fixture is replaced (where appropriate) with an `object_storage` fixture that multiplexes the test across both backends.
Unit tests are duplicated and for the GS versions use a boost test fixture for GCS, default local fake.

Fixes #25359
Fixes #26453

Closes scylladb/scylladb#26186

* github.com:scylladb/scylladb:
  docs::dev::object_storage: Add some initial info on GS storage
  docs/dev: Add mention of (nested) docker usage in testing.md
  sstables::object_storage_client: Forward memory limit semaphore to GS instance
  utils::gcp::object_storage: Add optional memory limits to up/download
  sstables::object_storage_client: Add multi-upload support for GS
  utils::gcp::storage: Add merge objects operation
  test_backup/test_basic: Make tests multiplex both s3 and gs backends
  test::cluster::conftest: Add support for multiple object storage backends
  boost::gcs_storage_test: reindent
  boost::gcs_storage_test: Convert to use fixture
  tests::boost: Add GS object storage cases to mirror S3 ones
  tests::lib::gcs_fixture: Add a reusable test fixture for real/fake GS/GCS
  tests::lib::test_utils: Add overloads/helpers for reading and (temp) writing env
  sstables::object_storage_client: Add google storage implementation
  test_services: Allow testing with GS object storage parameters
  utils::gcp::gcp_credentials: Add option to create uninitialized credentials
  utils::gcp::object_storage: Make create_download_source return seekable_data_source
  utils::gcp::object_storage: Add defensive copies of string_view params
  utils::gcp::object_storage: Add missing retry backoff increate
  utils::gcp::object_storage: Add timestamp to object listing
  utils::gcp::object_storage: Add paging support to list_objects
  object_storage_client: Add object_name wrapper type
  utils::gcp::object_storage: Add optional abort_source
  utils::rest::client: Add abort_source support
  sstables: Use object_storage_client for remote storage
  sstables::object_storage_client: Add abstraction layer for OS cliens (s3 initial)
  s3::upload_progress: Promote to general util type
  storage_options: Abstract s3 to "object_storage" and add gs as option
  sstables::file_io_extension: Change "creator" callback to just data_source
  utils::io-wrappers: Add ranged data_source
  utils::io-wrappers: Add file wrapper type for seekable_source
  utils::seekable_source: Add a seekable IO source type
  object_storage_endpoint_param: Add gs storage as option
  config: break out object_storage_endpoint_param preparing for multi storage
2025-10-20 13:14:53 +03:00
Tomasz Grabiec
c4a87453a2 Merge 'Add experimental feature flag for strongly consistent tables and extend kesypace creation syntax to allow specifying consistency mode.' from Gleb Natapov
The series adds an experimental flag for strongly consistent tables  and extends "CREATE KEYSPACE" ddl with `consistency` option that allows specifying the consistency mode for the keyspace.

Closes scylladb/scylladb#26116

* github.com:scylladb/scylladb:
  schema: Allow configuring consistency setting for a keyspace
  db: experimental consistent-tablets option
2025-10-16 21:48:06 +02:00
Nadav Har'El
921d07a26b cql: make SELECT's "internal page size" configurable
In some uses of SELECT, such as aggregation (sum() et al.), GROUP BY or
secondary index, it needs to perform internal scans. It uses an "internal
page size" which before this patch was always DEFAULT_COUNT_PAGE_SIZE = 10000.

There was an ad-hoc and undocumented way to override this default in C++
tests, using functions in test/lib/select_statement_utils.hh, but it
was so non-obvious that the test that most needed to override this
default - the very slow test test_indexing_paging_and_aggregation which
would have been must faster with a lower setting - never used it.

So in this patch we replace the ad-hoc configuration functions by a
bona-fide Scylla configuration option named "select_internal_page_size".

The few C++ tests that used the old configuration functions were
modified to use the new configuration parameters. The slow test
test_indexing_paging_and_aggregation still doesn't use the new
configuration to become faster - we'll do this in the next patch.

Another benefit of having this "internal page size" as a configuration
option is that one day a user might realize that the default choice
10,000 is bad for some reason (which I can't envision right now), so
having it configurable might come it handy.

Signed-off-by: Nadav Har'El <nyh@scylladb.com>
2025-10-15 18:42:09 +03:00
Gleb Natapov
eb9112a4a2 db: experimental consistent-tablets option
The option will be used to hid consistent tablets feature until it is
ready.
2025-10-15 11:27:10 +03:00
Calle Wilund
78d9dda060 config: break out object_storage_endpoint_param preparing for multi storage
Moves the config wrapper to own file (to reduce recompilation for modifying)
and refactors to handle extending this parameter to non-s3 endpoint configs.
2025-10-13 08:53:24 +00:00
Piotr Dulikowski
e7907b173a Merge 'db/view: Require rf_rack_valid_keyspaces when creating materialized view' from Dawid Mędrek
Materialized views are currently in the experimental phase and using them
in tablet-based keyspaces requires starting Scylla with an experimental feature,
`views-with-tablets`. Any attempts to create a materialized view or secondary
index when it's not enabled will fail with an appropriate error.

After considerable effort, we're drawing close to bringing views out of the
experimental phase, and the experimental feature will no longer be needed.
However, materialized views in tablet-based keyspaces will still be restricted,
and creating them will only be possible after enabling the configuration option
`rf_rack_valid_keyspaces`. That's what we do in this PR.

In this patch, we adjust existing tests in the tree to work with the new
restriction. That shouldn't have been necessary because we've already seemingly
adjusted all of them to work with the configuration option, but some tests hid
well. We fix that mistake now.

After that, we introduce the new restriction. What's more, when starting Scylla,
we verify that there is no materialized view that would violate the contract.
If there are some that do, we list them, notify the user, and refuse to start.

High-level implementation strategy:

1. Name the restrictions in form of a function.
2. Adjust existing tests.
3. Restrict materialized views by both the experimental feature
   and the configuration option. Add validation test.
4. Drop the requirement for the experimental feature. Adjust the added test
   and add a new one.
5. Update the user documentation.

Fixes scylladb/scylladb#23030

Backport: 2025.4, as we are aiming to support materialized views for tablets from that version.

Closes scylladb/scylladb#25802

* github.com:scylladb/scylladb:
  view: Stop requiring experimental feature
  db/view: Verify valid configuration for tablet-based views
  db/view: Require rf_rack_valid_keyspaces when creating view
  test/cluster/random_failures: Skip creating secondary indexes
  test/cluster/mv: Mark test_mv_rf_change as skipped
  test/cluster: Adjust MV tests to RF-rack-validity
  test/boost/schema_loader_test.cc: Explicitly enable rf_rack_valid_keyspaces
  db/view: Name requirement for views with tablets
2025-10-06 12:46:46 +02:00
Dawid Mędrek
b409e85c20 view: Stop requiring experimental feature
We modify the requirements for using materialized views in tablet-based
keyspaces. Before, it was necessary to enable the configuration option
`rf_rack_valid_keyspaces`, having the cluster feature `VIEWS_WITH_TABLETS`
enabled, and using the experimental feature `views-with-tablets`.
We drop the last requirement.

We adjust code to that change and provide a new validation test.
We also update the user documentation to reflect the changes.

Fixes scylladb/scylladb#23030
2025-10-01 09:01:53 +02:00
Nadav Har'El
926089746b message: move RPC compression from utils/ to message/
The directory utils/ is supposed to contain general-purpose utility
classes and functions, which are either already used across the project,
or are designed to be used across the project.

This patch moves 8 files out of utils/:

    utils/advanced_rpc_compressor.hh
    utils/advanced_rpc_compressor.cc
    utils/advanced_rpc_compressor_protocol.hh
    utils/stream_compressor.hh
    utils/stream_compressor.cc
    utils/dict_trainer.cc
    utils/dict_trainer.hh
    utils/shared_dict.hh

These 8 files together implement the compression feature of RPC.
None of them are used by any other Scylla component (e.g., sstables have
a different compression), or are ready to be used by another component,
so this patch moves all of them into message/, where RPC is implemented.

Theoretically, we may want in the future to use this cluster of classes
for some other component, but even then, we shouldn't just have these
files individually in utils/ - these are not useful stand-alone
utilities. One cannot use "shared_dict.hh" assuming it is some sort of
general-purpose shared hash table or something - it is completely
specific to compression and zstd, and specifically to its use in those
other classes.

Beyond moving these 8 files, this patch also contains changes to:
1. Fix includes to the 5 moved header files (.hh).
2. Fix configure.py, utils/CMakeLists.txt and message/CMakeLists.txt
   for the three moved source files (.cc).
3. In the moved files, change from the "utils::" namespace, to the
   "netw::" namespace used by RPC. Also needed to change a bunch
   of callers for the new namespace. Also, had to add "utils::"
   explicitly in several places which previously assumed the
   current namespace is "utils::".

Signed-off-by: Nadav Har'El <nyh@scylladb.com>

Closes scylladb/scylladb#25149
2025-09-30 17:03:09 +03:00
Avi Kivity
4d9271df98 Merge 'sstables: introduce sstable version ms' from Michał Chojnowski
This is yet another part in the BTI index project.

Overarching issue: https://github.com/scylladb/scylladb/issues/19191
Previous part: https://github.com/scylladb/scylladb/pull/25626
Next parts: make `ms` the default. Then, general tweaks and improvements. Later, potentially a full `da` format implementation.

This patch series introduces a new, Scylla-only sstable format version `ms`, which is like `me`, but with the index components (Summary.db and Index.db) replaced with BTI index components (Partitions.db and Rows.db), as they are in Cassandra 5.0's `da` format version.

(Eventually we want to just implement `da`, but there are several other changes (unrelated to the index files) between `me` and `da`. By adding this `ms` as an intermediate step we can adapt the new index formats without dragging all the other changes into the mix (and raising the risk of regressions, which is already high)).

The high-level structure of the PR is:
1. Introduce new component types — `Partitions` and `Rows`.
2. Teach `class sstable` to open them when they exist.
3. Teach the sstable writer how to write index data to them.
4. Teach `class sstable` and unit tests how to deal with sstables that have no `Index` or `Summary` (but have `Partitions` and `Rows` instead).
5. Introduce the new sstable version `ms`, specify that it has `Partitions` and `Rows` instead of `Index` and `Summary`.
6. Prepare unit tests for the appearance of `ms`.
7. Enable `ms` in unit tests.
8. Make `ms` enablable via db::config (with a silent fall back to `me` until the new `MS_SSTABLE_FORMAT` cluster feature is enabled).
9. Prepare integration tests for the appearance of `ms`.
10. Enable both `ms` and `me` in tests where we want both versions to be tested.

This series doesn't make `ms` the default yet, because that requires teaching Scylla Manager and a few dtests about the new format first. It can be enabled by setting `sstable_format: ms` in the config.

Per a review request, here is an example from `perf_fast_forward`, demonstrating some motivation for a new format. (Although not the main one. The main motivations are getting rid of restrictions on the RAM:disk ratio, and index read throughput for datasets with tiny partitions). The dataset was populated with `build/release/scylla perf-fast-forward --smp=1 --sstable-format=$VERSION --data-directory=data.$VERSION --column-index-size-in-kb=1 --populate --random-seed=0`.
This test involves a partition with 1000000 clustering rows (with 32-bit keys and 100-byte values) and ~500 index blocks, and queries a few particular rows from the partition. Since the branching factor for the BIG promoted index is 2 (it's a binary search), the lookup involves ~11.2 sequential page reads per row. The BTI format has a more reasonable branching factor, so it involves ~2.3 page reads per row.

`build/release/scylla perf-fast-forward --smp=1 --data-directory=perf_fast_forward_data/me --run-tests=large-partition-select-few-rows`:
```
offset  stride  rows     iterations    avg aio    aio      (KiB)
500000  1       1                70       18.0     18        128
500001  1       1               647       19.0     19        132
0       1000000 1               748       15.0     15        116
0       500000  2               372       29.0     29        284
0       250000  4               227       56.0     56        504
0       125000  8               116      106.0    106        928
0       62500   16               67      195.0    195       1732
```
`build/release/scylla perf-fast-forward --smp=1 --data-directory=perf_fast_forward_data/ms --run-tests=large-partition-select-few-rows`:
```
offset  stride  rows     iterations    avg aio    aio      (KiB)
500000  1       1                51        5.1      5         20
500001  1       1                64        5.3      5         20
0       1000000 1               679        4.0      4         16
0       500000  2               492        8.0      8         88
0       250000  4               804       16.0     16        232
0       125000  8               409       31.0     31        516
0       62500   16               97       54.0     54       1056
```

Index file size comparison for the default `perf_fast_forward` tables with `--random-seed=0`:
Large partition table (dominated by intra-partition index): 2.4 MB with `me`, 732 kB with `ms`.
For the small partitions table (dominated by inter-partition index): 11 MB with `me`, 8.4 MB with `ms`.

External tests:
I ran SCT test `longevity-mv-si-4days-streaming-test` test on 6 nodes with 30 shards each for 8 hours. No anomalies were observed.

New functionality, no backport needed.

Closes scylladb/scylladb#26215

* github.com:scylladb/scylladb:
  test/boost/bloom_filter_test: add test_rebuild_from_temporary_hashes
  test/cluster: add test_bti_index.py
  test: prepare bypass_cache_test.py for `ms` sstables
  sstables/trie/bti_index_reader: add a failure injection in advance_lower_and_check_if_present
  test/cqlpy/test_sstable_validation.py: prepare the test for `ms` sstables
  tools/scylla-sstable: add `--sstable-version=?` to `scylla sstable write`
  db/config: expose "ms" format to the users via database config
  test: in Python tests, prepare some sstable filename regexes for `ms`
  sstables: add `ms` to `all_sstable_versions`
  test/boost/sstable_3_x_test: add `ms` sstables to multi-version tests
  test/lib/index_reader_assertions: skip some row index checks for BTI indexes
  test/boost/sstable_inexact_index_test: explicitly use a `me` sstable
  test/boost/sstable_datafile_test: skip test_broken_promoted_index_is_skipped for `ms` sstables
  test/resource: add `ms` sample sstable files for relevant tests
  test/boost/sstable_compaction_test: prepare for `ms` sstables.
  test/boost/index_reader_test: prepare for `ms` sstables
  test/boost/bloom_filter_tests: prepare for `ms` sstables
  test/boost/sstable_datafile_test: prepare for `ms` sstables
  test/boost/sstable_test: prepare for `ms` sstables.
  sstables: introduce `ms` sstable format version
  tools/scylla-sstable: default to "preferred" sstable version, not "highest"
  sstables/mx/reader: use the same hashed_key for the bloom filter and the index reader
  sstables/trie/bti_index_reader: allow the caller to passing a precalculated murmur hash
  sstables/trie/bti_partition_index_writer: in add(), get the key hash from the caller
  sstables/mx: make Index and Summary components optional
  sstables: open Partitions.db early when it's needed to populate key range for sharding metadata
  sstables: adapt sstable::set_first_and_last_keys to sstables without Summary
  sstables: implement an alternative way to rebuild bloom filters for sstables without Index
  utils/bloom_filter: add `add(const hashed_key&)`
  sstables: adapt estimated_keys_for_range to sstables without Summary
  sstables: make `sstable::estimated_keys_for_range` asynchronous
  sstables/sstable: compute get_estimated_key_count() from Statistics instead of Summary
  replica/database: add table::estimated_partitions_in_range()
  sstables/mx: implement sstable::has_partition_key using a regular read
  sstables: use BTI index for queries, when present and enabled
  sstables/mx/writer: populate BTI index files
  sstables: create and open BTI index files, when enabled
  sstables: introduce Partition and Rows component types
  sstables/mx/writer: make `_pi_write_m.partition_tombstone` a `sstables::deletion_time`
2025-09-30 09:40:02 +03:00
Michał Chojnowski
ef11dc57c1 db/config: expose "ms" format to the users via database config
Extend the `sstable_format` config enum with a "ms" value,
and, if it's enabled (in the config and in cluster features),
use it for new sstables on the node.

(Before this commit, writing `ms` sstables should only be possible
in unit tests, via internal APIs. After this commit, the format
can be enabled in the config and the database will write it during
normal operation).

As of this commit, the new format is not the default yet.
(But it will become the default in a later commit in the same series).
2025-09-29 22:15:25 +02:00
Nadav Har'El
1aef733d48 Merge 'Alternator/cache expressions' from Szymon Malewski
Before this patch, every expression in Alternator's requests was parsed from string to adequate structure.
This patch enables caching, where input expression strings are mapped to parsed template structures.
Every new valid (parsable) expression is added to the cache. The cache has limited (configurable) size - when it is reached, the least recently used entry is removed.
When requested expression is in the cache, the copy of the template is returned - individual instances still need to be resolved (placeholders substituted with names and values).
Caching is implemented for all expression types. The cache is per shard - shared for all operations, expression types, tables, users.
Default cache size is 2000 entries per shard and it has configuration option `alternator_max_expression_cache_entries_per_shard` (0 means cache disabled).
Basic metrics (total count of hits and misses for each expression type and number of evicted enries) are implemented.
Cache features are tested in boost unit tests and overall expression caching is tested with Python tests - both mostly rely on metrics.

refs #5023
`perf-alternator` test shows improvement (median):
| test | throughput | instructions_per_op | cpu_cycles_per_op | allocs_per_op |
| ------ | ---------------- | ----------------------------- | --------------------------- | -------------------  |
| read | +6.0% | -8.5% | -7.0% | -4.9% |
| write | +13.4% | -17.6% | -14.7% | -7.4% |
| write(lwt) | +12.7% | -7.9% | -6.9% | -2.8% |
| write_rwm | +5.4% | -10.5% | -7.3% | -4.1% |

"read" had a ProjectionExpression with 10 column names, "write" had a UpdateExpression with 10 column names and "write_rmw" had both ConditionExpression and UpdateExpression.

This patch also includes minor refactoring of other expressions related tests (https://github.com/scylladb/scylladb/issues/22494) - use `test_table_ss` instead of `test_table`.
Fixes #25855.

This is new feature - no backporting.

Closes scylladb/scylladb#25176

* github.com:scylladb/scylladb:
  alternator: use expression caching
  alternator: adds expression cache implementation
  utils: extend lru_string_map
  utils: add lru_string_map
  alternator/expressions: error on parsing empty update expression
  alternator/expressions: fix single value condition expression parsing
  test/alternator: use `test_table_ss` instead of `test_table` in expressions related tests.
2025-09-29 11:36:31 +03:00
Szymon Malewski
6ce7843774 alternator: use expression caching
Before this patch, every expression in Alternator's requests was parsed from string to adequate structure.
This patch enables caching - all calls to parse an expression (all types) are proxied through the cache.
New expression is added to the cache, the least recently used entry (above cache size) is removed.
For existing entries the copy of the template is returned - individual instances still need to be resolved (placeholders substituted with names and values).
The cache is per shard - shared for all operations, expression types, tables, users.
Default cache size is 2000 entries per shard and it has configuration option `alternator_max_expression_cache_entries_per_shard` (0 means cache disabled).
Added Python tests are based on metrics.
2025-09-28 04:27:44 +02:00
Nikos Dragazis
e1d9c83406 db/config: Add SSTable compression options for user tables
ScyllaDB offers the `compression` DDL property for configuring
compression per user table (compression algorithm and chunk size). If
not specified, the default compression algorithm is the LZ4Compressor
with a 4KiB chunk size (refer to the default constructor for
`compression_parameters`). The same default applies to system tables as
well.

Add a new configuration option to allow customizing the default for user
tables. Use the previously hardcoded default as the new option's default
value.

Note that the option has no effect on ALTER TABLE statements. An altered
table either inherits explicit compression options from the CQL
statement, or maintains its existing options.

Signed-off-by: Nikos Dragazis <nikolaos.dragazis@scylladb.com>
2025-09-26 12:02:00 +03:00
Nikos Dragazis
a7e46974d4 db/config: Prepare compression_parameters for config system
SSTable compression is currently configurable only per table, via the
`compression` property in CREATE/ALTER TABLE statements. This is
represented internally via the `compression_parameters` class. We plan
to offer the same options via the configuration as well, to make the
default compression method for user tables configurable.

This patch prepares the ground by making the `compression_parameters`
usable as a `config_file::named_value`, namely:

* Define an extraction operator (required by `boost::program_options`
  for parsing the options from command line).
* Define a formatter (required by `named_value::operator()`).
* Define a template specialization for `config_type_for` (required by
  `named_value` constructor).
* Define a yaml converter (required for parsing the options from
  scylla.yaml).

Signed-off-by: Nikos Dragazis <nikolaos.dragazis@scylladb.com>
2025-09-24 14:51:39 +03:00
Karol Nowacki
eedf506be5 vector_store_client: Rename vector_store_uri to vector_store_primary_uri
The configuration setting vector_store_uri is renamed to
vector_store_primary_uri according to the final design.
In the future, the vector_store_secondary_uri setting will
be introduced.

This setting now also accepts a comma-separated list of URIs to prepare
for future support for redundancy and load balancing. Currently, only the
first URI in the list is used.

This change must be included before the next release.
Otherwise, users will be affected by a breaking change.

References: VECTOR-187

Closes scylladb/scylladb#26033
2025-09-21 16:33:10 +03:00
Michał Chojnowski
9e70df83ab db: get rid of sstables-format-selector
Our sstable format selection logic is weird, and hard to follow.

If I'm not misunderstanding, the pieces are:
1. There's the `sstable_format` config entry, which currently
   doesn't do anything, but in the past it used to disable
   cluster features for versions newer than the specified one.
2. There are deprecated and unused config entries for individual
   versions (`enable_sstables_mc_format`, `enable_sstables_md_format`,
   etc).
3. There is a cluster feature for each version:
   ME_SSTABLE_FORMAT, MD_SSTABLE_FORMAT, etc.
   (Currently all sstable version features have been grandfathered,
   and aren't checked by the code anymore).
4. There's an entry in `system.scylla_local` which contains the
   latest enabled sstable version. (Why? Isn't this directly derived
   from cluster features anyway)?
5. There's `sstable_manager::_format` which contains the
   sstable version to be used for new writes.
   This field is updated by `sstables_format_selector`
   based on cluster features and the `system.scylla_local` entry.

I don't see why those pieces are needed. Version selection has the
following constraints:
1. New sstables must be written with a format that supports existing
   data. For example, range tombstones with an infinite bound are only
   supported by sstables since version "mc". So if a range tombstone
   with an infinite bound exists somewhere in the dataset,
   the format chosen for new sstables has to be at least as new as "mc".
2. A new format might only be used after a corresponding cluster feature
   is enabled. (Otherwise new sstables might become unreadable if they
   are sent to another node, or if a node is downgraded).
3. The user should have a way to inhibit format ugprades if he wishes.

So far, constraint (1) has been fulfilled by never using formats older
than the newest format ever enabled on the node. (With an exception
for resharding and reshaping system tables).
Constraint (2) has been fulfilled by calling `sstable_manager::set_format`
only after the corresponsing cluster feature is enabled.
Constraint (3) has been fulfilled by the ability to inhibit cluster
features by setting `sstable_format` by some fixed value.

The main thing I don't like about this whole setup is that it doesn't
let me downgrade the preferred sstable format. After a format is
enabled, there is no way to go back to writing the old format again.
That is no good -- after I make some performance-sensitive changes
in a new format, it might turn out to be a pessimization for the
particular workload, and I want to be able to go back.

This patch aims to give a way to downgrade formats without violating
the constraints. What it does is:
1. The entry in `system.scylla_local` becomes obsolete.
   After the patch we no longer update or read it.
   As far as I understand, the purpose of this entry is to prevent
   unwanted format downgrades (which is something cluster features
   are designed for) and it's updated if and only if relevant
   cluster features are updated. So there's no reason to have it,
   we can just directly use cluster features.
2. `sstable_format_selector` gets deleted.
   Without the `system.scylla_local` around, it's just a glorified
   feature listener.
3. The format selection logic is moved into `sstable_manager`.
   It already sees the `db::config` and the `gms::feature_service`.
   For the foreseeable future, the knowledge of enabled cluster features
   and current config should be enough information to pick the right formats.
4. The `sstable_format` entry in `db::config` is no longer intended to
   inhibit cluster features. Instead, it is intended to select the
   format for new sstables, and it becomes live-updatable.
5. Instead of writing new sstables with "highest supported" format,
   (which used to be set by `sstables_format_selector`) we write
   them with the "preferred" format, which is determined by
   `sstable_manager` based on the combination of enabled features
   and the current value of `sstable_format`.

Closes scylladb/scylladb#26092

[avi: Pavel found the reason for the scylla_local entry -
      it predates stable storage for cluster features]
2025-09-19 16:17:56 +03:00
Łukasz Paszkowski
535c901e50 config: Add critical_disk_utilization_level option
The option defines the threshold at which the defensive mechanisms
preventing nodes from running out of space, e.g. rejecting user
writes shall be activated.

Its default value is 98% of the disk capacity.
2025-08-28 18:06:37 +02:00