The central idea of incremental repair is to allow repair participants
to select and repair only a portion of the dataset to speed up the
repair process. All repair participants must utilize an identical
selection method to repair and synchronize the same selected dataset.
There are two primary selection methods: time-based and file-based. The
time-based method selects data within a specified time frame. It is
versatile but it is less efficient because it requires reading all of
the dataset and omitting data beyond the time frame. The file-based
method selects data from unrepaired SSTables and is more efficient
because it allows the entire SSTable to be omitted. This document patch
implements the file-based selection method.
Incremental repair will only be supported for tablet tables; it will not
be supported for vnode tables. On one hand, the legacy vnode is less
important to support. On the other hand, the incremental repair for
vnode is much harder to implement. With vnodes, a SSTalbe could contain
data for multiple vnode ranges. When a given vnode range is repaired,
only a portion of the SSTable is repaired. This complicates the
manipulation of SSTables significantly during both repair and
compaction. With tablets, an entire tablet is repaired so that a
sstable is either fully repaired or not repaired which is a huge
simplification.
This patch uses the repaired_at from sstables::statistics component to
mark a sstable as repaired. It uses a virtual clock as the repair
timestamp, i.e., using a monotonically increasing number for the
repaired_at field of a SSTable and sstables_repaired_at column in
system.tablets table. Notice that when a sstable is not repaired, the
repaired_at field will be set to the default value 0 by default. The
being_repaired in memory field of a SSTable is used to explicitly mark
that a SSTable is being selected. The following variables are used for
incremental repair:
The repaired_at on disk field of a SSTable is used.
- A 64-bit number increases sequentially
The sstables_repaired_at is added to the system.tablets table.
- repaired_at <= sstables_repaired_at means the sstable is repaired
The being_repaired in memory field of a SSTable is added.
- A repair UUID tells which sstable has participated in the repair
Initial test results:
1) Medium dataset results
Node amount: 3
Instance type: i4i.2xlarge
Disk usage per node: ~500GB
Cluster pre-populated with ~500GB of data before starting repairs job.
Results for Repair Timings:
The regular repair run took 210 mins.
Incremental repair 1st run took 183 mins, 2nd and 3rd runs took around 48s
The speedup is: 183 mins / 48s = 228X
2) Small dataset results
Node amount: 3
Instance type: i4i.2xlarge
Disk usage per node: ~167GB
Cluster pre-populated with ~167GB of data before starting the repairs job.
Regular repair 1st run took 110s, 2nd and 3rd runs took 110s.
Incremental repair 1st run took 110 seconds, 2nd and 3rd run took 1.5 seconds.
The speedup is: 110s / 1.5s = 73X
3) Large dataset results
Node amount: 6
Instance type: i4i.2xlarge, 3 racks
50% of base load, 50% read/write
Dataset == Sum of data on each node
Dataset Non-incremental repair (minutes)
1.3 TiB 31:07
3.5 TiB 25:10
5.0 TiB 19:03
6.3 TiB 31:42
Dataset Incremental repair (minutes)
1.3 TiB 24:32
3.0 TiB 13:06
4.0 TiB 5:23
4.8 TiB 7:14
5.6 TiB 3:58
6.3 TiB 7:33
7.0 TiB 6:55
Fixes#22472Closesscylladb/scylladb#24291
* github.com:scylladb/scylladb:
replica: Introduce get_compaction_reenablers_and_lock_holders_for_repair
compaction: Move compaction_reenabler to compaction_reenabler.hh
topology_coordinator: Make rpc::remote_verb_error to warning level
repair: Add metrics for sstable bytes read and skipped from sstables
test.py: Disable incremental for test_tombstone_gc_for_streaming_and_repair
test.py: Add tests for tablet incremental repair
repair: Add tablet incremental repair support
compaction: Add tablet incremental repair support
feature_service: Add TABLET_INCREMENTAL_REPAIR feature
tablet_allocator: Add tablet_force_tablet_count_increase and decrease
repair: Add incremental helpers
sstable: Add being_repaired to sstable
sstables: Add set_repaired_at to metadata_collector
mutation_compactor: Introduce add operator to compaction_stats
tablet: Add sstables_repaired_at to system.tablets table
test: Fix drain api in task_manager_client.py
This patch addes incremental_repair support in compaction.
- The sstables are split into repaired and unrepaired set.
- Repaired and unrepaired set compact sperately.
- The repaired_at from sstable and sstables_repaired_at from
system.tablets table are used to decide if a sstable is repaired or
not.
- Different compactions tasks, e.g., minor, major, scrub, split, are
serialized with tablet repair.
Remove support for generating numerical sstable generation for new sstables.
Loading such sstables is still supported but new sstables are always created with a uuid generation.
This is possible since:
* All live versions (since 5.4 / f014ccf369) now support uuid sstable generations.
* The `uuid_sstable_identifiers_enabled` config option (that is unused from version 2025.2 / 6da758d74c) controls only the use of uuid generations when creating new sstables. SSTables with uuid generations should still be properly loaded by older versions, even if `uuid_sstable_identifiers_enabled` is set to `false`.
Fixes#24248
* Enhancement, no backport needed
Closesscylladb/scylladb#24512
* github.com:scylladb/scylladb:
streaming: stream_blob: use the table sstable_generation_generator
replica: distributed_loader: process_upload_dir: use the table sstable_generation_generator
sstables: sstable_generation_generator: stop tracking highest generation
replica: table: get rid of update_sstables_known_generation
sstables: sstable_directory: stop tracking highest_generation
replica: distributed_loader: stop tracking highest_generation
sstables: sstable_generation: get rid of uuid_identifiers bool class
sstables_manager: drop uuid_sstable_identifiers
feature_service: move UUID_SSTABLE_IDENTIFIERS to supported_feature_set
test: cql_query_test: add test_sstable_load_mixed_generation_type
test: sstable_datafile_test: move copy_directory helper to test/lib/test_utils
test: database_test: move table_dir helper to test/lib/test_utils
To combine the max purgable values, instead of just combining the
timestamp values. The former way is still correct, but loses the
timestamp explosion optimization, which allows the cache reader to drop
timestamps from the overlap checks.
It is not needed anymore.
With that database::_sstable_generation_generator can
be a regular member rather than optional and initialized
later.
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
It is returning constant sstables::uuid_identifiers::yes now,
so let the callers just use the constant (to be dropped
in a following patch).
Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Wired the unrepaired, repairing and repaired views into compaction_group.
Also the repaired filter was wired, so tablet_storage_group_manager
can implement the procedure to classify the sstable.
Based on this classifier, we can decide which view a sstable belongs
to, at any given point in time.
Additionally, we made changes changes to compaction_group_view
to return only sstables that belong to the underlying view.
From this point on, repaired, repairing and unrepaired sets are
connected to compaction manager through their views. And that
guarantees sstables on different groups cannot be compacted
together.
Repairing view specifically has compaction disabled on it altogether,
we can revert this later if we want, to allow repairing sstables
to be compacted with one another.
The benefit of this logical approach is having the classifier
as the single source of truth. Otherwise, we'd need to keep the
sstable location consistest with global metadata, creating
complexity
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
This will allow upcoming work to gently produce a sstable set for
each compaction group view. Example: repaired and unrepaired.
Locking strategy for compaction's sstable selection:
Since sstable retrieval path became futurized, tasks in compaction
manager will now hold the write lock (compaction_state::lock)
when retrieving the sstable list, feeding them into compaction
strategy, and finally registering selected sstables as compacting.
The last step prevents another concurrent task from picking the
same sstable. Previously, all those steps were atomic, but
we have seen stall in that area in large installations, so
futurization of that area would come sooner or later.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
In order to support incremental repair, we'll allow each
replica::compaction_group to have two logical compaction groups
(or logical sstable sets), one for repaired, another for unrepaired.
That means we have to adapt a few places to work with
compaction_group_view instead, such that no logical compaction
group is missed when doing table or tablet wide operations.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Since there will be only one physical sstable set, it makes sense to move
backlog tracker to replica::compaction_group. With incremental repair,
it still makes sense to compute backlog accounting both logical sets,
since the compound backlog influences the overall read amplification,
and the total backlog across repaired and unrepaired sets can help
driving decisions like giving up on incremental repair when unrepaired
set is almost as large as the repaired set, causing an amplification
of 2.
Also it's needed for correctness because a sstable can move quickly
across the logical sets, and having one tracker for each logical
set could cause the sstable to not be erased in the old set it
belonged to;
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Since table_state is a view to a compaction group, it makes sense
to rename it as so.
With upcoming incremental repair, each replica::compaction_group
will be actually two compaction groups, so there will be two
views for each replica::compaction_group.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Added a new POST endpoint `/storage_service/drop_quarantined_sstables` to the REST API.
This endpoint allows dropping all quarantined SSTables either globally or
for a specific keyspace and tables.
Optional query parameters `keyspace` and `tables` (comma-separated table names) can be
provided to limit the scope of the operation.
Fixesscylladb/scylladb#19061
Backport is not required, it is new functionality
Closesscylladb/scylladb#25063
* github.com:scylladb/scylladb:
docs: Add documentation for the nodetool dropquarantinedsstables command
nodetool: add command for dropping quarantine sstables
rest_api: add endpoint which drops all quarantined sstables
The plural overload of this method logs an error when the sstable add
fails. This is unnecessary, the caller is expected to catch and handle
exceptions. Furthermore, this unconditional error log results in
sporadic test failures, due to the unexpected error in the logs on
shutdown.
Fixes: #24850Closesscylladb/scylladb#25235
Added a new POST endpoint `/storage_service/drop_quarantined_sstables` to the REST API.
This endpoint allows dropping all quarantined SSTables either globally or
for a specific keyspace and tables.
Optional query parameters `keyspace` and `tables` (comma-separated table names) can be
provided to limit the scope of the operation.
Fixesscylladb/scylladb#19061
This change is preparing ground for state update unification for raft bound subsystems. It introduces schema_applier which in the future will become generic interface for applying mutations in raft.
Pulling database::apply() out of schema merging code will allow to batch changes to subsystems. Future generic code will first call prepare() on all implementations, then single database::apply() and then update() on all implementations, then on each shard it will call commit() for all implementations, without preemption so that the change is observed as atomic across all subsystems, and then post_commit().
Backport: no, it's a new feature
Fixes: https://github.com/scylladb/scylladb/issues/19649
Fixes https://github.com/scylladb/scylladb/issues/24531Closesscylladb/scylladb#24886
[avi: adjust for std::vector<mutations> -> utils::chunked_vector<mutations>]
* github.com:scylladb/scylladb:
test: add type creation to test_snapshot
storage_service: always wake up load balancer on update tablet metadata
db: schema_applier: call destroy also when exception occurs
db: replica: simplify seeding ERM during shema change
db: remove cleanup from add_column_family
db: abort on exception during schema commit phase
db: make user defined types changes atomic
replica: db: make keyspace schema changes atomic
db: atomically apply changes to tables and views
replica: make truncate_table_on_all_shards get whole schema from table_shards
service: split update_tablet_metadata into two phases
service: pull out update_tablet_metadata from migration_listener
db: service: add store_service dependency to schema_applier
service: simplify load_tablet_metadata and update_tablet_metadata
db: don't perform move on tablet_hint reference
replica: split add_column_family_and_make_directory into steps
replica: db: split drop_table into steps
db: don't move map references in merge_tables_and_views()
db: introduce commit_on_shard function
db: access types during schema merge via special storage
replica: make non-preemptive keyspace create/update/delete functions public
replica: split update keyspace into two phases
replica: split creating keyspace into two functions
db: rename create_keyspace_from_schema_partition
db: decouple functions and aggregates schema change notification from merging code
db: store functions and aggregates change batch in schema_applier
db: decouple tables and views schema change notifications from merging code
db: store tables and views schema diff in schema_applier
db: decouple user type schema change notifications from types merging code
service: unify keyspace notification functions arguments
db: replica: decouple keyspace schema change notifications to a separate function
db: add class encapsulating schema merging
Destructor of database_sstable_write_monitor, which is created
in table::try_flush_memtable_to_sstable, tries to get the compaction
state of the processed compaction group. If at this point
the compaction group is already stopped (and the compaction state
is removed), e.g. due to concurrent tablet merge, an exception is
thrown and a node coredumps.
Add flush gate to compaction group to wait for flushes in
compaction_group::stop. Hold the gate in seal function in
table::make_memtable_list. seal function is turned into
a coroutine to ensure it won't throw.
Wait until async_gate is closed before flushing, to ensure that
all data is written into sstables. Stop ongoing compactions
beforehand.
Remove unnecessary flush in tablet_storage_group_manager::merge_completion_fiber.
Stop method already flushes the compaction group.
Fixes: #23911.
Closesscylladb/scylladb#24582
Before for views and indexes it was fetching base schema from db (and
couple other properties). This is a problem once we introduce atomic
tables and views deletion (in the following commit).
Because once we delete table it can no longer be fetched from db object,
and truncation is performed after atomically deleting all relevant
tables/views/indexes.
Now the whole relevant schema will be fetched via global_table_ptr
(table_shards) object.
When a tablet transitions to a post-cleanup stage on the leaving replica
we deallocate its storage group. Before the storage can be deallocated
and destroyed, we must make sure it's cleaned up and stopped properly.
Normally this happens during the tablet cleanup stage, when
table::cleanup_table is called, so by the time we transition to the next
stage the storage group is already stopped.
However, it's possible that tablet cleanup did not run in some scenario:
1. The topology coordinator runs tablet cleanup on the leaving replica.
2. The leaving replica is restarted.
3. When the leaving replica starts, still in `cleanup` stage, it
allocates a storage group for the tablet.
4. The topology coordinator moves to the next stage.
5. The leaving replica deallocates the storage group, but it was not
stopped.
To address this scenario, we always stop the storage group when
deallocating it. Usually it will be already stopped and complete
immediately, and otherwise it will be stopped in the background.
Fixesscylladb/scylladb#24857Fixesscylladb/scylladb#24828Closesscylladb/scylladb#24896
When describing a table, we need to do it carefully: if some
columns were dropped, we must specify that explicitly by
```
ALTER TABLE {table} DROP {column} USING TIMESTAMP ...
```
in the result of the DESCRIBE statement. Failing to do so
could lead to data resurrection.
However, if a table has been altered many, many times,
we might end up with a huge create statement. Constructing
it could, in turn, trigger an oversized allocation.
Some tests ran into that very problem in fact.
In this commit, we want to mitigate the problem: instead of
allocating a contiguous chunk of memory for the create
statement, we use `fragmented_ostringstream` and `managed_string`
to possibly keep data scattered in memory. It makes handling
`cql3::description` less convenient in the code, but since
the struct is pretty much immediately serialized after
creating it, it's a very good trade-off.
We provide a reproducer. It consistently passes with this commit,
while having about 50% chance of failure before it (based on my
own experiments). Playing with the parameters of the test
doesn't seem to improve that chance, so let's keep it as-is.
Fixesscylladb/scylladb#24018
This reverts commit 0b516da95b, reversing
changes made to 30199552ac. It breaks
cluster.random_failures.test_random_failures.test_random_failures
in debug mode (at least).
Fixes#24513
When a tablet is migrated and cleaned up, deallocate the tablet storage
group state on `end_migration` stage, instead of `cleanup` stage:
* When the stage is updated from `cleanup` to `end_migration`, the
storage group is removed on the leaving replica.
* When the table is initialized, if the tablet stage is `end_migration`
then we don't allocate a storage group for it. This happens for
example if the leaving replica is restarted during tablet migration.
If it's initialized in `cleanup` stage then we allocate a storage
group, and it will be deallocated when transitioning to
`end_migration`.
This guarantees that the storage group is always deallocated on the
leaving replica by `end_migration`, and that it is always allocated if
the tablet wasn't cleaned up fully yet.
It is a similar case also for the pending replica when the migration is
aborted. We deallocate the state on `revert_migration` which is the
stage following `cleanup_target`.
Previously the storage group would be allocated when the tablet is
initialized on any of the tablet replicas - also on the leaving replica,
and when the tablet stage is `cleanup` or `end_migration`, and
deallocated during `cleanup`.
This fixes the following issue:
1. A migrating tablet enters cleanup stage
2. the tablet is cleaned up successfuly
3. The leaving replica is restarted, and allocates storage group
4. tablet cleanup is not called because it's already cleaned up
5. the storage group remains allocated on the leaving replica after the
migration is completed - it's not cleaned up properly.
Fixes https://github.com/scylladb/scylladb/issues/23481
backport to all relevant releases since it's a bug that results in a crash
Closesscylladb/scylladb#24393
* github.com:scylladb/scylladb:
test/cluster/test_tablets: test restart during tablet cleanup
test: tablets: add get_tablet_info helper
tablets: deallocate storage state on end_migration
This change is preparing ground for state update unification for raft bound subsystems. It introduces schema_applier which in the future will become generic interface for applying mutations in raft.
Pulling `database::apply()` out of schema merging code will allow to batch changes to subsystems. Future generic code will first call `prepare()` on all implementations, then single `database::apply()` and then `update()` on all implementations, then on each shard it will call `commit()` for all implementations, without preemption so that the change is observed as atomic across all subsystems, and then `post_commit()`.
Backport: no, it's a new feature
Fixes: https://github.com/scylladb/scylladb/issues/19649Closesscylladb/scylladb#20853
* github.com:scylladb/scylladb:
storage_service: always wake up load balancer on update tablet metadata
db: schema_applier: call destroy also when exception occurs
db: replica: simplify seeding ERM during shema change
db: remove cleanup from add_column_family
db: abort on exception during schema commit phase
db: make user defined types changes atomic
replica: db: make keyspace schema changes atomic
db: atomically apply changes to tables and views
replica: make truncate_table_on_all_shards get whole schema from table_shards
service: split update_tablet_metadata into two phases
service: pull out update_tablet_metadata from migration_listener
db: service: add store_service dependency to schema_applier
service: simplify load_tablet_metadata and update_tablet_metadata
db: don't perform move on tablet_hint reference
replica: split add_column_family_and_make_directory into steps
replica: db: split drop_table into steps
db: don't move map references in merge_tables_and_views()
db: introduce commit_on_shard function
db: access types during schema merge via special storage
replica: make non-preemptive keyspace create/update/delete functions public
replica: split update keyspace into two phases
replica: split creating keyspace into two functions
db: rename create_keyspace_from_schema_partition
db: decouple functions and aggregates schema change notification from merging code
db: store functions and aggregates change batch in schema_applier
db: decouple tables and views schema change notifications from merging code
db: store tables and views schema diff in schema_applier
db: decouple user type schema change notifications from types merging code
service: unify keyspace notification functions arguments
db: replica: decouple keyspace schema change notifications to a separate function
db: add class encapsulating schema merging
When a tablet is migrated and cleaned up, deallocate the tablet storage
group state on `end_migration` stage, instead of `cleanup` stage:
* When the stage is updated from `cleanup` to `end_migration`, the
storage group is removed on the leaving replica.
* When the table is initialized, if the tablet stage is `end_migration`
then we don't allocate a storage group for it. This happens for
example if the leaving replica is restarted during tablet migration.
If it's initialized in `cleanup` stage then we allocate a storage
group, and it will be deallocated when transitioning to
`end_migration`.
This guarantees that the storage group is always deallocated on the
leaving replica by `end_migration`, and that it is always allocated if
the tablet wasn't cleaned up fully yet.
It is a similar case also for the pending replica when the migration is
aborted. We deallocate the state on `revert_migration` which is the
stage following `cleanup_target`.
Previously the storage group would be allocated when the tablet is
initialized on any of the tablet replicas - also on the leaving replica,
and when the tablet stage is `cleanup` or `end_migration`, and
deallocated during `cleanup`.
This fixes the following issue:
1. A migrating tablet enters cleanup stage
2. the tablet is cleaned up successfuly
3. The leaving replica is restarted, and allocates storage group
4. tablet cleanup is not called because it was already cleaned up
4. the storage group remains allocated on the leaving replica after the
migration is completed - it's not cleaned up properly.
Fixesscylladb/scylladb#23481
The table::take_snapshot() touches the snapshot directory, which is
good. It happens on all shards, which is not that good, because all
shards just step on each other toes when doing it, the directory is not
sharded. Same for post-snapshot directory sync -- it can happen once,
after all shards finish creating snapshot links.
Move both, touching and syncing up one level. There's only one caller of
the method, so only one caller to update.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Closesscylladb/scylladb#24154
Truncate doesn't really go well with concurrent writes. The fix (#23560) exposed
a preexisting fragility which I missed.
1) truncate gets RP mark X, truncated_at = second T
2) new sstable written during snapshot or later, also at second T (difference of MS)
3) discard_sstables() get RP Y > saved RP X, since creation time of sstable
with RP Y is equal to truncated_at = second T.
So the problem is that truncate is using a clock of second granularity for
filtering out sstables written later, and after we got low mark and truncate time,
it can happen that a sstable is flushed later within the same second, but at a
different millisecond.
By switching to a millisecond clock (db_clock), we allow sstables written later
within the same second from being filtered out. It's not perfect but
extremely unlikely a new write lands and get flushed in the same
millisecond we recorded truncated_at timepoint. In practice, truncate
will not be used concurrently to writes, so this should be enough for
our tests performing such concurrent actions.
We're moving away from gc_clock which is our cheap lowres_clock, but
time is only retrieved when creating sstable objects, which frequency of
creation is low enough for not having significant consequences, and also
db_clock should be cheap enough since it's usually syscall-less.
Fixes#23771.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Closesscylladb/scylladb#24426
Before for views and indexes it was fetching base schema from db (and
couple other properties). This is a problem once we introduce atomic
tables and views deletion (in the following commit).
Because once we delete table it can no longer be fetched from db object,
and truncation is performed after atomically deleting all relevant
tables/views/indexes.
Now the whole relevant schema will be fetched via global_table_ptr
(table_shards) object.
Consider the following scenario:
1) let's assume tablet 0 has range [1, 5] (pre merge)
2) tablet merge happens, tablet 0 has now range [1, 10]
3) tablet_sstable_set isn't refreshed, so holds a stale state, thinks tablet 0 still has range [1, 5]
4) during a full scan, forward service will intersect the full range with tablet ranges and consume one tablet at a time
5) replica service is asked to consume range [1, 10] of tablet 0 (post merge)
We have two possible outcomes:
With cache bypass:
1) cache reader is bypassed
2) sstable reader is created on range [1, 10]
3) unrefreshed tablet_sstable_set holds stale state, but select correctly all sstables intersecting with range [1, 10]
With cache:
1) cache reader is created
2) finds partition with token 5 is cached
3) sstable reader is created on range [1, 4] (later would fast forward to range [6, 10]; also belongs to tablet 0)
4) incremental selector consumes the pre-merge sstable spanning range [1, 5]
4.1) since the partitioned_sstable_set pre-merge contains only that sstable, EOS is reached
4.2) since EOS is reached, the fast forward to range [6, 10] is not allowed.
So with the set refreshed, sstable set is aligned with tablet ranges, and no premature EOS is signalled, otherwise preventing fast forward to from happening and all data from being properly captured in the read.
This change fixes the bug and triggers a mutation source refresh whenever the number of tablets for the table has changed, not only when we have incoming tablets.
Additionally, includes a fix for range reads that span more than one tablet, which can happen during split execution.
Fixes: https://github.com/scylladb/scylladb/issues/23313
This change needs to be backported to all supported versions which implement tablet merge.
Closesscylladb/scylladb#24287
* github.com:scylladb/scylladb:
replica: Fix range reads spanning sibling tablets
test: add reproducer and test for mutation source refresh after merge
tablets: trigger mutation source refresh on tablet count change
Consider the following scenario:
- let's assume tablet 0 has range [1, 5] (pre merge)
- tablet merge happens, tablet 0 has now range [1, 10]
- tablet_sstable_set isn't refreshed, so holds a stale state, thinks tablet
0 still has range [1, 5]
- during a full scan, forward service will intersect the full range with
tablet ranges and consume one tablet at a time
- replica service is asked to consume range [1, 10] of tablet 0 (post merge)
We have two possible outcomes:
With cache bypass:
1) cache reader is bypassed
2) sstable reader is created on range [1, 10]
3) unrefreshed tablet_sstable_set holds stale state, but select correctly
all sstables intersecting with range [1, 10]
With cache:
1) cache reader is created
2) finds partition with token 5 is cached
3) sstable reader is created on range [1, 4] (later would fast forward to
range [6, 10]; also belongs to tablet 0)
4) incremental selector consumes the pre-merge sstable spanning range [1, 5]
4.1) since the partitioned_sstable_set pre-merge contains only that sstable,
EOS is reached
4.2) since EOS is reached, the fast forward to range [6, 10] is not allowed.
So with the set refreshed, sstable set is aligned with tablet ranges, and no
premature EOS is signalled, otherwise preventing fast forward to from
happening and all data from being properly captured in the read.
This change fixes the bug and triggeres a mutation source refresh whenever
the number of tablets for the table has changed, not only when we have
incoming tablets.
Fixes: #23313
Currently, when a max purgeable timestamp is computed, there is no
information where it comes from and how the value was obtained.
Take compaction, if there are memtables or other uncompacting sstables
possibly shadowing data, the timestamp is decreased to ensure a
tombstone is not purged but the caller does not know what that the
timestamp has its value.
In this patch, we extend the return type of max_purgeable_fn to
contain not only a timestamp but also an information on how it was
computed. This information will be required to collect statistics
on tombstone purge failures due to overlapping memtables/uncompacting
sstables that come later in the series.
Following a number of similar code cleanup PR, this one aims to be the last one, definitely dropping flat from all reader and related names.
Similarly, v2 is also dropped from reader names, although it still persists in mutation_fragment_v2, mutation_v2 and related names. This won't change in the foreseeable future, as we don't have plans to drop mutation (the v1 variant).
The changes in this PR are entirely mechanical, mostly just search-and-replace.
Code cleanup, no backport required.
Closesscylladb/scylladb#24087
* github.com:scylladb/scylladb:
test/boost/mutation_reader_another_test: drop v2 from reader and related names
test/boost/mutation_reader: s/puppet_reader_v2/puppet_reader/
test/boost/sstable_datafile_test: s/sstable_reader_v2/sstable_mutation_reader/
test/boost/mutation_test: s/consumer_v2/consumer/
test/lib/mutation_reader_assertions: s/flat_reader_assertions_v2/mutation_reader_assertions/
readers/mutation_readers: s/generating_reader_v2/generating_reader/
readers/mutation_readers: s/delegating_reader_v2/delegating_reader/
readers/mutation_readers: s/empty_flat_reader_v2/empty_mutation_reader/
readers/mutation_source: s/make_reader_v2/make_mutation_reader/
readers/mutation_source: s/flat_reader_v2_factory_type/mutation_reader_factory/
readers/mutation_reader: s/reader_consumer_v2/mutation_reader_consumer/
mutation/mutation_compactor: drop v2 from compactor and related names
replica/table: s/make_reader_v2/make_mutation_reader/
mutation_writer: s/bucket_writer_v2/bucket_writer/
readers/queue: drop v2 from reader and related names
readers/multishard: drop v2 from reader and related names
readers/evictable: drop v2 from reader and related names
readers/multi_range: remove flat from name
Some background:
When merge happens, a background fiber wakes up to merge compaction
groups of sibling tablets into main one. It cannot happen when
rebuilding the storage group list, since token metadata update is
not preemptable. So a storage group, post merge, has the main
compaction group and two other groups to be merged into the main.
When the merge happens, those two groups are empty and will be
freed.
Consider this scenario:
1) merge happens, from 2 to 1 tablet
2) produces a single storage group, containing main and two
other compaction groups to be merged into main.
3) take_storage_snapshot(), triggered by migration post merge,
gets a list of pointer to all compaction groups.
4) t__s__s() iterates first on main group, yields.
5) background fiber wakes up, moves the data into main
and frees the two groups
6) t__s__s() advances to other groups that are now freed,
since step 5.
7) segmentation fault
In addition to memory corruption, there's also a potential for
data to escape the iteration in take_storage_snapshot(), since
data can be moved across compaction groups in background, all
belonging to the same storage group. That could result in
data loss.
Readers should all operate on storage group level since it can
provide a view on all the data owned by a tablet replica.
The movement of sstable from group A to B is atomic, but
iteration first on A, then later on B, might miss data that
was moved from B to A, before the iteration reached B.
By switching to storage group in the interface that retrieves
groups by token range, we guarantee that all data of a given
replica can be found regardless of which compaction group they
sit on.
Fixes#23162.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Closesscylladb/scylladb#24058
When schema is changed, sstable set is updated according to the compaction
strategy of the new schema (no changes to set are actually made, just
the underlying set type is updated), but the problem is that it happens
without a lock, causing a use-after-free when running concurrently to
another set update.
Example:
1) A: sstable set is being updated on compaction completion
2) B: schema change updates the set (it's non deferring, so it
happens in one go) and frees the set used by A.
3) when A resumes, system will likely crash since the set is freed
already.
ASAN screams about it:
SUMMARY: AddressSanitizer: heap-use-after-free sstables/sstable_set.cc ...
Fix is about deferring update of the set on schema change to compaction,
which is triggered after new schema is set. Only strategy state and
backlog tracker are updated immediately, which is fine since strategy
doesn't depend on any particular implementation of sstable set, since
patch "sstables: Implement sstable_set_impl::all_sstable_runs()".
Fixes#22040.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Interval map is very susceptible to quadratic space behavior when
it's flooded with many entries overlapping all (or most of)
intervals, since each such entry will have presence on all
intervals it overlaps with.
A trigger we observed was memtable flush storm, which creates many
small "L0" sstables that spans roughly the entire token range.
Since we cannot rely on insertion order, solution will be about
storing sstables with such wide ranges in a vector (unleveled).
There should be no consequence for single-key reads, since upper
layer applies an additional filtering based on token of key being
queried.
And for range scans, there can be an increase in memory usage,
but not significant because the sstables span an wide range and
would have been selected in the combined reader if the range of
scan overlaps with them.
Anyway, this is a protection against storm of memtable flushes
and shouldn't be the common scenario.
It works both with tablets and vnodes, by adjusting the token
range spanned by compaction group accordingly.
Fixes#23634.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
This provides a way for compaction layer to know compaction group's
token range. It will be important for sstable set impl to know
the token range of underlying group.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
In the previous commits we made sure that the base info is not dependent
on the base schema version, and the info dependent on the base schema
version is calculated when it's needed. In this patch we remove the
unnecessary re-setting of the base_info.
The set_base_info method isn't removed completely, because it also has
a secondary function - zeroing the view_info fields other than base_info.
Because of this, in this patch we rename it accordingly and limit its
use to the updates caused by a base schema change.
The base info in view schemas no longer changes on base schema
updates, so saving the base info with a view schema from a specific
point in time doesn't provide any additional benefits.
In this patch we remove the code using the base_and_view snapshots
as it's no longer useful.
In the following patch we plan to remove the base schema from the base_info
to make the base_info immutable. To do that, we first prepare the schema
registry for the change; we need to be able to create view schemas from
frozen schemas there and frozen schemas have no information about the base
table. Unless we do this change, after base schemas are removed from the
base info, we'll no longer be able to load a view schema to the schema registry
without looking up the base schema in the database.
This change also required some updates to schema building:
* we add a method for unfreezing a view schema with base info instead of
a base schema
* we make it possible to use schema_builder with a base info instead of
a base schema
* we add a method for creating a view schema from mutations with a base info
instead of a base schema
* we add a view_info constructor withat base info instead of a base schema
* we update the naming in schema_registry to reflect the usage of base info
instead of base schema
