This is in preparation for the following patch that adds abort_source
variable to the sstables_manager.
Signed-off-by: Lakshmi Narayanan Sreethar <lakshmi.sreethar@scylladb.com>
It was added to make integration of storage groups easier, but it's
complicated since it's another source of truth and we could have
problems if it becomes inconsistent with the group map.
Fixes#18506.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
We currently disable tombstone GC for compaction done on the read path of streaming and repair, because those expired tombstones can still prevent data resurrection. With time-based tombstone GC, missing a repair for long enough can cause data resurrection because a tombstone is potentially GC'd before it could be spread to every node by repair. So repair disseminating these expired tombstones helps clusters which missed repair for long enough. It is not a guarantee because compaction could have done the GC itself, but it is better than nothing.
This last resort is getting less important with repair-based tombstone GC. Furthermore, we have seen this cause huge repair amplification in a cluster, where expired tombstones triggered repair replicating otherwise identical rows.
This series makes tombstone GC on the streaming/repair compaction path configurable with a config item. This new config item defaults to `false` (current behaviour), setting it to `true`, will enable tombstone GC.
Fixes: https://github.com/scylladb/scylladb/issues/19015
Not a regression, no backport needed
Closesscylladb/scylladb#19016
* github.com:scylladb/scylladb:
test/topology_custom/test_repair: add test for enable_tombstone_gc_for_streaming_and_repair
replica/table: maybe_compact_for_streaming(): toggle tombstone GC based on the control flag
replica: propagate enable_tombstone_gc_for_streaming_and_repair to maybe_compact_for_streaming()
db/config: introduce enable_tombstone_gc_for_streaming_and_repair
Currently, a pending replica that applies a write on a table that has
materialized views, will build all the view updates as a normal replica,
only to realize at a late point, in db::view::get_view_natural_endpoint(),
that it doesn't have a paired view replica to send the updates to. It will
then either drop the view updates, or send them to a pending view
replica, if such exists.
This work is unnecessary since it may be dropped, and even if there is a
pending view replica to send the updates to, the updates that are built
by the pending replica may be wrong since it may have incomplete
information.
This commit fixes the inefficiency by skipping the view update building
step when applying an update on a pending replica.
The metric total_view_updates_on_wrong_node is added to count the cases
that a view update is determined to be unnecessary.
The test reproduces the scenario of writing to a table and applying
the update on a pending replica, and verifies that the pending replica
doesn't try to build view updates.
Fixesscylladb/scylladb#19152Closesscylladb/scylladb#19488
flat_mutation_reader_v2 was introduced in a pair of commits in 2021:
e3309322c3 "Clone flat_mutation_reader related classes into v2 variants"
08b5773c12 "Adapt flat_mutation_reader_v2 to the new version of the API"
as a replacement for flat_mutation_reader, using range_tombstone_change
instead of range_tombstone to represent represent range tombstones. See
those commits for more information.
The transition was incremental; the last use of the original
flat_mutation_reader was removed in 2022 in commit
026f8cc1e7 "db: Use mutation_partition_v2 in mvcc"
In turn, flat_mutation_reader was introduced in 2017 in commit
748205ca75 "Introduce flat_mutation_reader"
To transition from a mutation_reader that nested rows within
a partition in a separate stream, to a flat reader that streamed
partitions and rows in the same stream.
Here, we reclaim the original name and rename the awkward
flat_mutation_reader_v2 to mutation_reader.
Note that mutation_fragment_v2 remains since we still use the original
for compatibilty, sometimes.
Some notes about the transition:
- files were also renamed. In one case (flat_mutation_reader_test.cc), the
rename target already existed, so we rename to
mutation_reader_another_test.cc.
- a namespace 'mutation_reader' with two definitions existed (in
mutation_reader_fwd.hh). Its contents was folded into the mutation_reader
class. As a result, a few #includes had to be adjusted.
Closesscylladb/scylladb#19356
Normally, the space overhead for TWCS is 1/N, where is number of windows. But during off-strategy, the overhead is 100% because input sstables cannot be released earlier.
Reshaping a TWCS table that takes ~50% of available space can result in system running out of space.
That's fixed by restricting every TWCS off-strategy job to 10% of free space in disk. Tables that aren't big will not be penalized with increased write amplification, as all input (disjoint) sstables can still be compacted in a single round.
Fixes#16514.
Closesscylladb/scylladb#18137
* github.com:scylladb/scylladb:
compaction: Reduce twcs off-strategy space overhead to 10% of free space
compaction: wire storage free space into reshape procedure
sstables: Allow to get free space from underlying storage
replica: don't expose compaction_group to reshape task
compaction_group sits in replica layer and compaction layer is
supposed to talk to it through compaction::table_state only.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
those functions cannot return nullptr, will throw when group is not
found, so better return ref instead.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
When a function is created with the CREATE FUNCTION statement, the
statement handler does all the necessary preparations on its own. The
very same code exists in schema_tables, when the function is loaded on
boot. This patch generalizes both and keeps function language-specific
context creation inside lang/ code.
The creation function returns context via argument reference. It would
have been nicer if it was returned via future<>, but it's not suitable
for future<T> type :(
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
And, while at it, rename local variable to refer to it to as "manager"
not "wasm". Query processor and database also have getters named
"wasm()", these are not renamed yet to keep patch smaller (and those
getters are going to be reworked further anyway).
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
This vector of paths is only used to generate the same vector of paths
for table config, but the latter already has all the needed info.
It's the part of the plan to stop using paths/directories in keyspaces
and tables, because with storage-options tables no longer keep their
data in "files on disk", so this information goes to sstables storage
manager (refs #12707)
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Closesscylladb/scylladb#19119
tablet snapshot, used by migration, can race with compaction and
can find files deleted. That won't cause data loss because the
error is propagated back into the coordinator that decides to
retry streaming stage. So the consequence is delayed migration,
which might in turn reduce node operation throughput (e.g.
when decommissioning a node). It should be rare though, so
shouldn't have drastic consequences.
Fixes#18977.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Closesscylladb/scylladb#18979
Retrieval of tablet stats must be serialized with mutation to token metadata, as the former requires tablet id stability.
If tablet split is finalized while retrieving stats, the saved erm, used by all shards, can have a lower tablet count than the one in a particular shard, causing an abort as tablet map requires that any id feeded into it is lower than its current tablet count.
Fixes#18085.
Closesscylladb/scylladb#18287
* github.com:scylladb/scylladb:
test: Fix flakiness in topology_experimental_raft/test_tablets
service: Use tablet read selector to determine which replica to account table stats
storage_service: Fix race between tablet split and stats retrieval
If tablet split is finalized while retrieving stats, the saved erm, used by all
shards, will be invalidated. It can either cause incorrect behavior or
crash if id is not available.
It's worked by feeding local tablet map into the "coordinator"
collecting stats from all shards. We will also no longer have a snapshot
of erm shared between shards to help intra-node migration. This is
simplified by serializing token metadata changes and the retrieval of
the stats (latter should complete pretty fast, so it shouldn't block
the former for any significant time).
Fixes#18085.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Currently, we do not explicitly set a scheduling group for the schema
commitlog which causes it to run in the default scheduling group (called
"main"). However:
- It is important and significant enough that it should run in a
scheduling group that is separate from the main one,
- It should not run in the existing "commitlog" group as user writes may
sometimes need to wait for schema commitlog writes (e.g. read barrier
done to learn the schema necessary to interpret the user write) and we
want to avoid priority inversion issues.
Therefore, introduce a new scheduling group dedicated to the schema
commitlog.
Fixes: scylladb/scylladb#15566Closesscylladb/scylladb#18715
There's a set of API endpoints that toggle per-table auto-compaction and tombstone-gc booleans. They all live in two different .cc files under api/ directory and duplicate code of each other. This PR generalizes those handlers, places them next to each other, fixes leak on stop and, as a nice side effect, enlightens database.hh header.
Closesscylladb/scylladb#18703
* github.com:scylladb/scylladb:
api,database: Move auto-compaction toggle guard
api: Move some table manipulation helpers from storage_service
api: Move table-related calls from storage_service domain
api: Reimplement some endpoints using existing helpers
api: Lost unset of tombstone-gc endpoints
Toggling per-table auto-compaction enabling bit is guarded with
on-database boolean and raii guard. It's only used by a single
api/column_family.cc file, so it can live there.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
This series is a reupload of #13792 with a few modifications, namely a test is added and the conflicts with recent tablet related changes are fixed.
See https://github.com/scylladb/scylladb/issues/12379 and https://github.com/scylladb/scylladb/pull/13583 for a detailed description of the problem and discussions.
This PR aims to extend the existing throttling mechanism to work with requests that internally generate a large amount of view updates, as suggested by @nyh.
The existing mechanism works in the following way:
* Client sends a request, we generate the view updates corresponding to the request and spawn background tasks which will send these updates to remote nodes
* Each background task consumes some units from the `view_update_concurrency_semaphore`, but doesn't wait for these units, it's just for tracking
* We keep track of the percent of consumed units on each node, this is called `view update backlog`.
* Before sending a response to the client we sleep for a short amount of time. The amount of time to sleep for is based on the fullness of this `view update backlog`. For a well behaved client with limited concurrency this will limit the amount of incoming requests to a manageable level.
This mechanism doesn't handle large DELETE queries. Deleting a partition is fast for the base table, but it requires us to generate a view update for every single deleted row. The number of deleted rows per single client request can be in the millions. Delaying response to the request doesn't help when a single request can generate millions of updates.
To deal with this we could treat the view update generator just like any other client and force it to wait a bit of time before sending the next batch of updates. The amount of time to wait for is calculated just like in the existing throttling code, it's based on the fullness of `view update backlogs`.
The new algorithm of view update generation looks something like this:
```c++
for(;;) {
auto updates = generate_updates_batch_with_max_100_rows();
co_await seastar::sleep(calculate_sleep_time_from_backlogs());
spawn_background_tasks_for_updates(updates);
}
```
Fixes: https://github.com/scylladb/scylladb/issues/12379Closesscylladb/scylladb#16819
* github.com:scylladb/scylladb:
test: add test for bad_allocs during large mv queries
mv: throttle view update generation for large queries
exceptions: add read_write_timeout_exception, a subclass of request_timeout_exception
db/view: extract view throttling delay calculation to a global function
view_update_generator: add get_storage_proxy()
storage_proxy: make view backlog getters public
With intra-node migration, all the movement is local, so we can make
streaming faster by just cloning the sstable set of leaving replica
and loading it into the pending one.
This cloning is underlying storage specific, but s3 doesn't support
snapshot() yet (th sstables::storage procedure which clone is built
upon). It's only supported by file system, with help of hard links.
A new generation is picked for new cloned sstable, and it will
live in the same directory as the original.
A challenge I bumped into was to understand why table refused to
load the sstable at pending replica, as it considered them foreign.
Later I realized that sharder (for reads) at this stage of migration
will point only to leaving replica. It didn't fail with mutation
based streaming, because the sstable writer considers the shard --
that the sstable was written into -- as its owner, regardless of what
sharder says. That was fixed by mimicking this behavior during
loading at pending.
test:
./test.py --mode=dev intranode --repeat=100 passes.
Signed-off-by: Raphael S. Carvalho <raphaelsc@scylladb.com>
Require users to specify whether we want shard for reads or for writes
by switching to appropriate non-deprecated variant.
For example, shard_of() can be replaced with shard_for_reads() or
shard_for_writes().
The next_shard/token_for_next_shard APIs have only for-reads variant,
and the act of switching will be a testimony to the fact that the code
is valid for intra-node migration.
The namespace replica is broken in the middle with sstable_list alias,
while the latter can be declared earlier
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Closesscylladb/scylladb#18664
This patch adds a test for reproducing issue #12379, which is
being fixed in #16819.
The test case works by creating a table with a materialized
view, and then performing a partition delete query on it.
At the same time, it uses injections to limit the memory
to a level lower than usual, in order to increase the
consistency of the test, and to limit its runtime.
Before #16819, the test would exceed the limit and fail,
and now the next allocation is throttled using a sleep.
Closesscylladb/scylladb#18616
* github.com:scylladb/scylladb:
replica: Make it explicit table's sstable set is immutable
replica: avoid reallocations in tablet_sstable_set
replica: Avoid compound set if only one sstable set is filled
Currently empty storage_groups are allocated for tablets that are
not on this shard.
Allocate storage groups dynamically, i.e.:
- on table creation allocate only storage groups that are on this
shard;
- allocate a storage group for tablet that is moved to this shard;
- deallocate storage group for tablet that is cleaned up.
Stop compaction group before it's deallocated.
Add a flag to table::cleanup_tablet deciding whether to deallocate
sgs and use it in commitlog tests.
Add rwlock which prevents storage groups from being added/deleted
while some other layers itereates over them (or their compaction
groups).
Add methods to iterate over storage groups with the lock held.
Pass compaction group id to
shard_reshaping_compaction_task_impl::reshape_compaction_group.
Modify table::as_table_state to return table_state of the given
compaction group.
Currently we have a single method -- detach_column_family() -- which
does something with each semaphore. Soon there will be another one.
Introduce a method to do something with all semaphores, to make this
smoother. Enterprise has a different set of semaphores, and this will
reduce friction.
The populate_views() and generate_and_propagate_view_updates() both naturally belong to view_update_generator -- they don't need anything special from table itself, but rather depend on some internals of the v.u.generator itself.
Moving them there lets removing the view concurrency semaphore from keyspace and table, thus reducing the cross-components dependencies.
Closesscylladb/scylladb#18421
* github.com:scylladb/scylladb:
replica: Do not carry view concurrency semaphore pointer around
view: Get concurrency semaphore via database, not table
view_update_generator: Mark mutate_MV() private
view: Move view_update_generator methods' code
view: Move table::generate_and_propagate_view_updates into view code
view: Move table::populate_views() into view_update_generator class
There are two places that get total:live stats for a table snapshot --
database::get_snapshot_details() and table::get_snapshot_details(). Both
do pretty similar thing -- walk the table/snapshots/ directory, then
each of the found sub-directory and accumulate the found files' sizes
into snapshot details structure.
Both try to tell total from live sizes by checking whether an sstable
component found in snapshots is present in the table datadir. The
database code does it in a more correct way -- not just checks the file
presense, but also compares if it's a hardlink on the snapshot file,
while the table code just checks if the file of the same name exists.
This patch does both -- makes both database and table call the same
helper method for a single snapshot details, and makes the generalized
version use more elaborated collision check, thus fixing the per-table
details getting behavior.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Closesscylladb/scylladb#18347
The _view_update_concurrency_sem field on database propagates itself via
keyspace config down to table config and view_update_generator then
grabs one via table:: helper. That's an overkil, view_update_generator
has direct reference on the database and can get this semaphore from
there.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Similarly to populate_views() method, this one also naturally belongs to
view_update_generator class.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
The method in question has little to do with table, effectively it only
needs stats and consurrency semaphore. And the semaphore in question is
obtained from table indirectly, it really resides on database. On the
other hand, the method carries lots of bits from db::view, e.g. the
view_update_builder class, memory_usage_of() helper and a bit more.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
There's a database::get_snapshot_details() method that returns collection of all snapshots for all ks.cf out there and there are several *snapshot_details* aux structures around it. This PR keeps only one "details" and cleans up the way it propagates from database up to the respective API calls.
Closesscylladb/scylladb#18317
* github.com:scylladb/scylladb:
snapshot_ctl: Brush up true_snapshots_size() internals
snapshot_ctl: Remove unused details struct
snapshot_ctl: No double recoding of details
database,snapshots: Move database::snapshot_details into snapshot_ctl
database,snapshots: Make database::get_snapshot_details() return map, not vector
table,snapshots: Move table::snapshot_details into snapshot_ctl
So that it's in-sync with table::get_snapshot_details(). Next patches
will improve this place even further.
Also, there can be many snapshots and vector can grow large, but that's
less of an issue here.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
Now database is constructed with sharded<directory_semaphore>, but it no
longer needs sharded, local is enough.
Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
