Commit Graph

4972 Commits

Author SHA1 Message Date
Nadav Har'El
da99dc3a7f cross-tree: change to_sstring_view() to to_string_view()
For historic reasons, we have (in bytes.hh) a type sstring_view which
is an alias for std::string_view - since the same standard type can hold
a pointer into both a seastar::sstring and std::string.

This alias in unnecessary and misleading to new developers (who might
assume it is somehow different from std::string_view). This patch doesn't
yet remove all occurances of sstring_view (the request in #4062), but
begins to do it by renaming one commonly-used function, to_sstring_view(bytes)
to to_string_view() and of course changes all its uses to the new name.

Signed-off-by: Nadav Har'El <nyh@scylladb.com>
2024-11-18 14:57:49 +02:00
Tomasz Grabiec
8738d9bfa0 system_tables: Compute schema version automatically
This depends on the previous change to the schema_builder
which makes version computation depend on definition only
instead of being new time uuid.

This way we avoid the possibility for a common mistake
when schema of a system table is extended but we forget
to bump up its version passed to .with_version().
2024-11-15 19:16:41 +01:00
Kefu Chai
00810e6a01 treewide: include seastar/core/format.hh instead of seastar/core/print.hh
The later includes the former and in addition to `seastar::format()`,
`print.hh` also provides helpers like `seastar::fprint()` and
`seastar::print()`, which are deprecated and not used by scylladb.

Previously, we include `seastar/core/print.hh` for using
`seastar::format()`. and in seastar 5b04939e, we extracted
`seastar::format()` into `seastar/core/format.hh`. this allows us
to include a much smaller header.

In this change, we just include `seastar/core/format.hh` in place of
`seastar/core/print.hh`.

Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>

Closes scylladb/scylladb#21574
2024-11-14 17:45:07 +02:00
Avi Kivity
b58dbe57aa Merge 'repair: introduce and use buffer size hint for mixed-shard multishard reader' from Botond Dénes
Add a buffer hint to the multishard reader. This is an internal hint, used by the multishard reader to provide a hint to the shard reader, on how much data exactly is needed by the multishard reader from the respective shard. This hint allows eliminating extraneous cross-shard round-trips and possible shard reader evict-recreate cycles. Building on this, repair sets its own row buffer size as the max buffer size on the multishard reader, ensuring that the row buffer is filled with the minimum amount of cross-shard round trips and minimal reader recreation.
To further eliminate unnecessary evictions, this PR also disables the multishard reader's read-ahead which is a mechanism that was designed to reduce latency for user-reads but it can be too aggressive for repair, causing unnecessary extra congestion on the already struggling streaming semaphores.

Refs: https://github.com/scylladb/scylladb/issues/18269
Fixes: https://github.com/scylladb/scylladb/issues/21113

The performance impact was measured with an SCT test, which creates a cluster of 3 nodes with 16 shards, then adds a 4th one with 12 shards.
Currently, it is the bootstrap time which is the worse in the case of mixed shard clusters, see below for the improvement measured during bootstrap:

|              | master        | buffer-hint   | metric                                              |
| ------------ | ------------- | ------------- | --------------------------------------------------- |
| evictions    |          0.9M |         93.0K | scylla_database_paused_reads_permit_based_evictions |
| read (bytes) |          9.0T |          3.9T | scylla_reactor_aio_bytes_read                       |
| read (ops)   |         88.0M |         33.5M | scylla_reactor_aio_reads                            |
| time         |         56min |         20min | N/A                                                 |

This is a performance improvement, no backport required.

Closes scylladb/scylladb#20815

* github.com:scylladb/scylladb:
  test/boost/mutation_reader_test: add test for multishard reader buffer hint
  repair/row_level: disable read-ahead
  db/config: introduce repair_multishard_reader_enable_read_ahead
  readers/multishard: implement the read_ahead flag
  replica/database: make_multishard_streaming_reader(): expose the read_ahead parameter
  readers/multishard: add read_ahead parameter
  repair/row_level: set max buffer size on multishard reader
  replica/database: make_multishard_streaming_reader(): expose buffer_hint parameter
  db/config: introduce enable_repair_multishard_reader_buffer_hint
  readers/multishard: multishard_reader: pass hint to shard_reader
  readers/multishard: shard_reader_v2::fill_reader_buffer(): respect the hint
  readers/multishard: propagate fill_buffer_hint to shard_reader:fill_reader_buffer()
  readers/multishard: shard_reader: extract buffer-fill into its own method
2024-11-10 12:55:19 +02:00
Botond Dénes
e3e8a94c9a Merge 'Allow explicitly enabling or disabling tablets when creating a new keyspace' from Benny Halevy
Separate the configuration for enabling the tablets feature from the enablement of tablets when creating new keyspaces.

This change always enables the TABLETS cluster feature and the tablets logic respectively.

The `enable_tablets` config option just controls whether tablets are enabled or disabled by default for new keyspaces.

If `enable_tablets` is set to `true`, tablets can be disabled using `CREATE KEYSPACE WITH tablets = { 'enabled': false }` as it is today.

If `enable_tablets` is set to `false`, tablets can be enabled using `CREATE KEYSPACE WITH tablets = { 'enabled': true }`.

The motivation for this change is to simplify the user experience of using tablets by setting the default for new keyspaces to false amd allowing the user to simply opt-in by using tablets = {enabled: true }.
This is not pissible today.
The user has to enable tablets by default for all new keyspaces (that use the NetworkTopologyStrategy) and then actively opt-out to use vnodes.

* Not required to be backported to OSS versions.  May be backported to specific enterprise versions

* This PR resubmits https://github.com/scylladb/scylladb/pull/20729 that was reverted in 73b1f66b70 due to https://github.com/scylladb/scylladb/issues/21159 which is now fixed

Closes scylladb/scylladb#21451

* github.com:scylladb/scylladb:
  data_dictionary: keyspace_metadata::describe: print tablets enabled also when defaulted
  tablets_test: test enable/disable tablets when creating a new keyspace
  treewide: always allow tablets keyspaces
  feature_service: prevent enabling both tablets and gossip topology changes
  alternator: create_keyspace_metadata: enable tablets using feature_service
2024-11-08 09:15:42 +02:00
Benny Halevy
4b21cca443 treewide: always allow tablets keyspaces
With the tablets feature always enabled (Unless gossip toopology
changes are forced), the enable_tablets option now controls only
the default for newly created keyspaces.

Even when set to `false`, tablets are still enabled as a
feature and the user may explicitly enable tablets
using `CREATE KEYSPACE <name> WITH tablets = {'enabled': true}`

Note: best viewed with `git show -w`

Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
2024-11-07 13:57:39 +02:00
Benny Halevy
974b0f2080 feature_service: prevent enabling both tablets and gossip topology changes
Tablets require raft consistent topology changes.
Therefore, document that they are incompatible in
the config help and prevent their usage in
`feature_config_from_db_config`

Fixes scylladb/scylladb#21075

Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
2024-11-07 13:56:59 +02:00
Botond Dénes
a248520201 db/config: introduce repair_multishard_reader_enable_read_ahead
Not used yet.
2024-11-07 02:47:54 -05:00
Avi Kivity
f5489ba4a1 locator: tablet_metadata_guard: forward declare database
No need to bring in a heavy databas.hh dependency.

Closes scylladb/scylladb#21447
2024-11-07 10:24:35 +03:00
Pavel Emelyanov
49949092ad Merge 'Make s3 client ops use abort source + use in backup task' from Calle Wilund
Fixes #20716

Adds optional abort_source to all s3 client operations. If provided, will propagate to actual HTTP client and allow for aborting actual net op.

Note: this uses an abort source per call, not a client-local one.
This is for two reasons:

1.) The usage pattern of the client object is to create it outside the eventual owning object (task) that hosts the relevant abort source
2.) It is quite possible to want to have different/no abort source for some operation usage.

Also adds forward usage of task abort_source in backup tasks upload s3 call, making it more readily abort-able.

Closes scylladb/scylladb#21431

* github.com:scylladb/scylladb:
  backup_task: Use task abort source in s3 client call
  s3::client: Make operations (individually) abortable
2024-11-07 10:03:25 +03:00
Calle Wilund
0db4b9fd94 backup_task: Use task abort source in s3 client call
Fixes #20716

Propagates abort source in task object to actual network call,
thus making the upload workload more quickly abortable.

v2: Fix test to handle two versions after each other
2024-11-06 15:20:23 +00:00
Botond Dénes
3c25e6fcb4 db/config: introduce enable_repair_multishard_reader_buffer_hint
Allows enabling/disabling the multishard reader buffer hint
optimization. Not wired yet.
2024-11-06 08:51:00 -05:00
Kefu Chai
59eb2ab119 treewide: s/boost::algorithm::any_of/std::ranges::any_of/
now that we are allowed to use C++23. we now have the luxury of using
`std::ranges::any_of`.

in this change, we replace `boost::algorithm::any_of` with
`std::ranges::any_of`

to reduce the dependency to boost for better maintainability, and
leverage standard library features for better long-term support.

this change is part of our ongoing effort to modernize our codebase
and reduce external dependencies where possible.

Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
2024-11-05 14:06:09 +08:00
Avi Kivity
ee92784098 serialization: replace boost::type with std::type_identity
Recently, seastar rpc started accepting std::type_identity in addition
to boost::type as a type marker (while labeling the latter with an
ominous deprecation warning). Reduce our depedendency on boost
by switching to std::type_identity.
2024-11-05 00:43:27 +01:00
Botond Dénes
19a43b5859 Merge 'repair: Reduce hints and batchlog flush' from Asias He
The hints and batchlog flush requests are issued to all nodes for each repair request when tombstone_gc repair mode is used.

The amount of such flush requests is high when all nodes in the cluster run repair. It is observed it takes a long time, up to 15s, for a repair request to finish such a flush request.

To reduce overhead of the flush, each node caches the flush and only executes the real flush when some time has passed. It is safe to do so before the real flush_time is returned. Repair uses the smallest flush_time from peers as the repair time.

The nice thing about the cache on the receiver side is that all senders can hit the cache. It is better than cache on the sender side.

A slightly smaller flush_time compared to the real flush time will be used with the benefits of significantly dropped hints and batchlog flush. The tradeoff is reasonable.

Fixes #20259

Performance improvement. No backports.

Closes scylladb/scylladb#20260

* github.com:scylladb/scylladb:
  test/test_repair.py: Add test_batchlog_flush_in_repair
  repair: Reduce hints and batchlog flush
  db/batchlog_manager: Add add_delay_to_batch_replay
  db/batchlog_manager: Add get_last_replay
  db/batchlog_manager: wire in batchlog_replay_cleanup_after_replays
  db/config: introduce batchlog_replay_cleanup_after_replays
  db/batchlog_manager: do_batch_log_replay(): add cleanup flag
2024-11-01 14:23:27 +02:00
Botond Dénes
0ee0dd3ef4 Merge 'Collect and report backup progress' from Pavel Emelyanov
Task manager GET /status method returns two counters that reflect task progress -- total and completed. To make caller reason about their meaning, additionally there's progress_units field next to those counters.

This patch implements this progress report for backup task. The units are bytes, the total counter is total size of files that are being uploaded, and the completed counter is total amount of bytes successfully sent with PUT requests. To get the counters, the client::upload_file() is extended to calculate those.

fixes #20653

Closes scylladb/scylladb#21144

* github.com:scylladb/scylladb:
  backup_task: Report uploading progress
  s3/client: Account upload progress for real
  s3/client: Introduce upload_progress
  s3: Extract client_fwd.hh
2024-11-01 10:57:12 +02:00
Avi Kivity
8c67f9b42e cql3: util: remove unneeded boost/range includes from header files
The includes are redistributed to the source files that need them.

Closes scylladb/scylladb#21391
2024-10-31 23:49:44 +01:00
Nadav Har'El
ee2d75b088 Merge 'Generalize "breakpoint" type of error injection' from Pavel Emelyanov
This pattern is -- if requested (by test) suspend code execution until requestor (the test) explicitly wakes it up. For that the injected place should inject a lambda that is called with so called "handler" at hand and try to read message from the handler. In many cases the inner lambda additionally prints a message into logs that tests waits upon to make sure injection was stepped on. In the end of the day this "breakpoint" is injected like

```
    co_await inject("foo", [] (auto& handler) {
        log.info("foo waiting");
        co_await handler.wait_for_message(timeout);
    });
```

This PR makes breakpoints shorter and more unified, like this

```
    co_await inject("foo", wait_for_message(timeout));
```

where `wait_for_message` is a wrapper structure used to pick new `inject()` overload.

Closes scylladb/scylladb#21342

* github.com:scylladb/scylladb:
  sstables: Use inject(wait_for_message_overload)
  treewide,error_injection: Use inject(wait_for_message) and fix tests
  treewide,error_injection: Use inject(wait_for_message) overload
  error_injection: Add inject() overload with wait_for_message wrapper
2024-10-31 21:56:27 +02:00
Wojciech Mitros
88ab8db944 mv: run view building in streaming scheduling group
View building is an expensive process that takes a long time to complete.
During the build, it's impact on other work should be minimized, even at
the expense of slightly slowing it down.

Instead, view building is currently performed in the the same scheduling
group (gossip) as other high-priority tasks, in particular raft processing,
which slows it down, making races more likely and increasing the number
of retries that need to be done.

While view building is still initiated in the gossip group (as it's the
result of adding a view, which is a schema change), in this patch the bulk
of the view building work is moved to a low-priority, maintenance scheduling
group (named "streaming" after its main use case).

Additionally, a test is added, where we make sure that the scheduling
group is the one most used when building a view.

Fixes https://github.com/scylladb/scylladb/issues/21232

Closes scylladb/scylladb#21326
2024-10-31 10:13:20 +01:00
Avi Kivity
907da210b6 compound_compat: replace use of boost ranges with std ranges
To reduce the dependency load, replace use of boost ranges
with the std equivalent.

Files that lost the indirect boost dependency have it added as a
direct dependency.
2024-10-30 19:58:07 +02:00
Pavel Emelyanov
39cb93be3c treewide,error_injection: Use inject(wait_for_message) and fix tests
This is continuation of previous patch, this time also update tests that
wait for specific message in logs (to make sure injection handler was
called and paused the code execution).

Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
2024-10-30 16:53:33 +03:00
Pavel Emelyanov
7d8cc3ccc2 treewide,error_injection: Use inject(wait_for_message) overload
Many places want to inject a handler that waits for external kick. Now
there's convenience inject() method overload for this. It will result in
extra messages in logs, but so far no code/test cares about it.

Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
2024-10-30 16:53:33 +03:00
Asias He
b3b3e880d3 repair: Reduce hints and batchlog flush
The hints and batchlog flush requests are issued to all nodes for each
repair request when tombstone_gc repair mode is used.

The amount of such flush requests is high when all nodes in the cluster
run repair. It is observed it takes a long time, up to 15s, for a repair
request to finish such a flush request.

To reduce overhead of the flush, each node caches the flush and only
executes the real flush when the cahce time has passed. It is safe to do
so because the real flush_time is returned. Repair uses the smallest
flush_time returned from peers as the repair time.

The nice thing about the cache on the receiver side is that all senders
can hit the cache. It is better than cache on the sender side.

A slightly smaller flush_time compared to the real flush time will be
used with the benefits of significantly dropped hints and batchlog
flush. The trade-off looks reasonable.

Tests: 2 nodes, with 1s batchlog delay:

Before:
   Repair nr_repairs=20 cache_time_in_ms=0 total_repair_duration=40.04245328903198

After:
   Repair nr_repairs=20 cache_time_in_ms=5000 total_repair_duration=1.252073049545288

Fixes #20259
2024-10-30 11:07:57 +08:00
Asias He
f8ad78ba1e db/batchlog_manager: Add add_delay_to_batch_replay
It is used to simulate slow replay.
2024-10-30 11:07:57 +08:00
Asias He
fed9b54664 db/batchlog_manager: Add get_last_replay
It is used to get the time when the last replay is executed.
2024-10-30 11:07:57 +08:00
Botond Dénes
3361542e84 db/batchlog_manager: wire in batchlog_replay_cleanup_after_replays
After the specified amount of replays, trigger a cleanup: flush batchlog
table memtables. This allows the cleanup to happen on a configurable
interval, instead of on every batchlog replay attempt, which might be
too much.
2024-10-30 11:07:57 +08:00
Botond Dénes
1635525526 db/config: introduce batchlog_replay_cleanup_after_replays
Not used yet.
2024-10-30 11:07:57 +08:00
Botond Dénes
169c74346d db/batchlog_manager: do_batch_log_replay(): add cleanup flag
Add a flag controlling whether cleanup (memtable flush) will be done
after the replay. This is to allow repair to opt out from cleanup --
when many concurrenty repairs are running, there can be storms of calles
to do_batch_log_replay(), which will be mostly no-op, but they will all
attempt to flush the memtable to clean-up after themselves. This is
unnecessary and introduces latency to repairs, best to leave the cleanup
to the periodic batch-log replay.
2024-10-30 11:07:57 +08:00
Avi Kivity
73b1f66b70 Revert "Merge 'Allow explicitly enabling or disabling tablets when creating a new keyspace' from Benny Halevy"
This reverts commit c286434e4c, reversing
changes made to 6712fcc316.

The commit causes memtable_test to be very flaky in debug mode.
Specifically, subtests test_exceptions_in_flush_on_sstable_open
and test_exceptions_in_flush_on_sstable_write).
2024-10-30 00:55:29 +02:00
Pavel Emelyanov
25ae3d0aed backup_task: Report uploading progress
Do it by passing reference to s3::upload_progress_monitor object that
sits on task impl itself. Different files' uploads would then update the
monitor with their sizes and uploaded counters. The structure is
reported by get_progress() method. Unit size is set to be bytes. Test is
updated.

Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
2024-10-29 08:40:35 +03:00
Pavel Emelyanov
f9a5e02b53 s3: Extract client_fwd.hh
This is to export some simple structures to users without the need to
include client.hh itself (rather large already)

Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
2024-10-29 08:38:39 +03:00
Avi Kivity
c286434e4c Merge 'Allow explicitly enabling or disabling tablets when creating a new keyspace' from Benny Halevy
Separate the configuration for enabling the tablets feature from the enablement of tablets when creating new keyspaces.

This change always enables the TABLETS cluster feature and the tablets logic respectively.

The `enable_tablets` config option just controls whether tablets are enabled or disabled by default for new keyspaces.

If `enable_tablets` is set to `true`, tablets can be disabled using `CREATE KEYSPACE WITH tablets = { 'enabled': false }` as it is today.

If `enable_tablets` is set to `false`, tablets can be enabled using `CREATE KEYSPACE WITH tablets = { 'enabled': true }`.

The motivation for this change is to simplify the user experience of using tablets by setting the default for new keyspaces to false amd allowing the user to simply opt-in by using tablets = {enabled: true }.
This is not pissible today.
The user has to enable tablets by default for all new keyspaces (that use the NetworkTopologyStrategy) and then actively opt-out to use vnodes.

* Not required to be backported to OSS versions.  May be backported to specific enterprise versions

Closes scylladb/scylladb#20729

* github.com:scylladb/scylladb:
  data_dictionary: keyspace_metadata::describe: print tablets enabled also when defaulted
  tablets_test: test enable/disable tablets when creating a new keyspace
  treewide: always allow tablets keyspaces
  feature_service: prevent enabling both tablets and gossip topology changes
  alternator: create_keyspace_metadata: enable tablets using feature_service
2024-10-28 21:33:17 +02:00
Kefu Chai
9f8adcd207 backup_task: track the first failure uploading sstables
before this change, we only record the exception returned
by `upload_file()`, and rethrow the exception. but the exception
thrown by `update_file()` not populated to its caller. instead, the
exceptional future is ignored on pupose -- we need to perform
the uploads in parallel.  this is why the task is not marked fail
even if some of the uploads performed by it fail.

in this change, we

- coroutinize `backup_task_impl::do_backup()`. strictly speaking,
  this is not necessary to populate the exception. but, in order
  to ensure that the possible exception is captured before the
  gate is closed, and to reduce the intentation, the teardown
  steps are performed explicitly.
- in addition to note down the exception in the logging message,
  we also store it in a local variable, which it rethrown
  before this function returns.

Fixes scylladb/scylladb#21248
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>

Closes scylladb/scylladb#21254
2024-10-28 12:54:27 +03:00
Kefu Chai
24d14b601b treewide: s/boost::adaptors::map_values/std::views::values/
now that we are allowed to use C++23. we now have the luxury of using
`std::views::values`.

in this change, we:

- replace `boost::adaptors::map_values` with `std::views::values`
- update affected code to work with `std::views::values`
- the places where we use `boost::join()` are not changed, because
  we cannot use `std::views::concat` yet. this helper is only
  available in C++26.

to reduce the dependency to boost for better maintainability, and
leverage standard library features for better long-term support.

this change is part of our ongoing effort to modernize our codebase
and reduce external dependencies where possible.

Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>

Closes scylladb/scylladb#21265
2024-10-27 21:32:45 +02:00
Kefu Chai
e7d6ab576b backup_task: remove unused member variable
Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>

Closes scylladb/scylladb#21258
2024-10-25 11:49:06 +03:00
Benny Halevy
b0e12cb40d treewide: always allow tablets keyspaces
With the tablets feature always enabled (Unless gossip toopology
changes are forced), the enable_tablets option now controls only
the default for newly created keyspaces.

Even when set to `false`, tablets are still enabled as a
feature and the user may explicitly enable tablets
using `CREATE KEYSPACE <name> WITH tablets = {'enabled': true}`

Note: best viewed with `git show -w`

Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
2024-10-24 10:18:42 +03:00
Benny Halevy
bc62407421 feature_service: prevent enabling both tablets and gossip topology changes
Tablets require raft consistent topology changes.
Therefore, document that they are incompatible in
the config help and prevent their usage in
`feature_config_from_db_config`

Fixes scylladb/scylladb#21075

Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
2024-10-24 10:18:42 +03:00
Nadav Har'El
5fd3177057 Merge 'mv: add a dedicated read concurrency semaphore for view update read before writes' from Wojciech Mitros
When writing to some tables with materialized views, we need to read from the base table first to perform a delete of the old view row. When doing so, the memory used for the read is tracked by the user read concurrency semaphore. When we have a large number of such reads, we may use up all of the semaphore units, causing the following reads to be queued. When we have some user reads coming at the same time, these reads can have very high latency due to the write workload on the base table. We want to avoid this, so that the write workload doesn't have a high impact on the latency of the read workload.

This is fixed in this patch by adding a separate read concurrency semaphore just for view update read-before-writes. With the new semaphore, even if there are many view update read-before-writes, they will be queued on a different semaphore than the user reads, and they won't impact their latency.

The second issue fixed by this patch is the concurrency of the view updates that is currently unlimited. Because of that view updates may take up so much memory that they we may run out of memory.

This is fixed by using the read admission on the view update concurrency semaphore.
This limits the number of concurrent view update reads to
max_count_concurrent_view_update_reads, all other incoming view update reads are
queued using just a small chunk of memory. Without this, the reads would also get
queued after exceeding view_update_reader_concurrency_semaphore_serialize_limit_multiplier, but they would take much more memory while staying in the queue.

The new semaphore has half the capacity of the regular user read concurrency semahpore and is currently used only for user writes - is't used independently of the scheduling group on which we base the read semaphore selection, but we use a different code path for streaming (not database::do_apply) and we shouldn't have view updates in system writes or during compaction.

This patch also adds a test to confirm that the view update workload doesn't impact the read latency, as well as a test which confirms that we do not run out of memory even under heavy view udpate workload.

The issue of view updates causing increased latencies most often occurs in the following scenario:
* we have a medium to high write workload to a table with a materialized view which requires reading from the base table before sending the update to delete the old rows
* we have any read workload
* one replica is slower or is handling more writes due to an imbalance of data distribution
* we write with a cl<ALL, the mentioned replica is replying to write requests slower while new ones keep being sent to it.
* each write performs a read first taking resources from the user read concurrency semaphore, so when enough writes accumulate the reads using the semaphore start getting queued
* the queue is shared by regular reads and view update reads. When there's enough view update reads in the queue, regular reads start getting increased latencies

An sct test (perf-regression-latency-mv-read-concurrency) was prepared to somewhat resemble this scenario:
* the tables were prepared satisfying the conditions above
* we use a medium write workload and a very low read workload
* the imbalance is achieved by writing to just a few (10) partitions - some replicas (and shards) can have twice or more used partitions than others. We also keep writing to a limited (though high) number of rows, to cause overwrites which require reading before sending the view update
* to minimize the test case, we use a cluster of 3 nodes and rf=2, we write with cl=ONE to have background replica writes and read with cl=ALL to wait for the slower replica to respond.

In the test above:
* without the fix, the latency of reads increases over 50s
* with the fix, the latency of reads stays below 20ms

Fixes https://github.com/scylladb/scylladb/issues/8873
Fixes https://github.com/scylladb/scylladb/issues/15805

The patch is not that small and it isn't fixing a regression, so no backports

Closes scylladb/scylladb#20887

* github.com:scylladb/scylladb:
  test: add test for high view update concurrency causing bad_allocs
  test: add test for high view update concurrency degrading read latency
  mv: add a dedicated read concurrency semaphore for view update read before writes
2024-10-22 22:17:23 +03:00
Avi Kivity
847c850034 schema: add accessors for primary key columns and non-primary-key columns
It's somewhat common to ask for the partition key and clustering key
columns, or for the static and regular columsn. Provide accessors for them
rather than requiring the user to glue them.

Some callers are converted.

Closes scylladb/scylladb#21191
2024-10-22 15:01:14 +02:00
Kefu Chai
6ead5a4696 treewide: move log.hh into utils/log.hh
the log.hh under the root of the tree was created keep the backward
compatibility when seastar was extracted into a separate library.
so log.hh should belong to `utils` directory, as it is based solely
on seastar, and can be used all subsystems.

in this change, we move log.hh into utils/log.hh to that it is more
modularized. and this also improves the readability, when one see
`#include "utils/log.hh"`, it is obvious that this source file
needs the logging system, instead of its own log facility -- please
note, we do have two other `log.hh` in the tree.

Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>
2024-10-22 06:54:46 +03:00
Wojciech Mitros
f2c740710c test: add test for high view update concurrency degrading read latency
This commit add a test for checking whether a large view update workload
impacts the latency of other user reads.
In the test, we first create a table for reads and another table with
a materialized view. We then start writing to the table with the view
with a limited number of rows - when overwriting, we need to read the
previous value of the row to prepare a delete of the old row in the view.
This should not impact the latency of the read workload from the other
table that we start at the same time. The test fails if any of the reads
times out.
To reach the failing state more consistantly, we use add a sleep after
reading the old value of the base row, to keep the reader concurrency
semaphore units longer. At the same time, we use a lower threshold for
queueing reads on the semaphore, to see the impact of view update reads
earlier.
Because of the high load, the writes may timeout, but that's expected
- we fail the test only if the user reads time out.
2024-10-21 12:34:55 +02:00
Kefu Chai
5cd619a60c treewide: s/boost::adaptors::map_keys/std::views::keys/
now that we are allowed to use C++23. we now have the luxury of using
`std::views::keys`.

in this change, we:

- replace `boost::adaptors::map_keys` with `std::views::keys`
- update affected code to work with `std::views::keys`

to reduce the dependency to boost for better maintainability, and
leverage standard library features for better long-term support.

this change is part of our ongoing effort to modernize our codebase
and reduce external dependencies where possible.

Signed-off-by: Kefu Chai <kefu.chai@scylladb.com>

Closes scylladb/scylladb#21198
2024-10-21 12:47:52 +03:00
Wojciech Mitros
242079d70b mv: add a dedicated read concurrency semaphore for view update read before writes
When writing to some tables with materialized views, we need to read from the base
table first to perform a delete of the old view row. When doing so, the memory used
for the read is tracked by the user read concurrency semaphore. When we have a large
number of such reads, we may use up all of the semaphore units, causing the following
reads to be queued. When we have some user reads coming at the same time, these reads
can have very high latency due to the write workload on the base table. We want to avoid
this, so that the write workload doesn't have a high impact on the latency of the
read workload.

This is fixed in this patch by adding a separate read concurrency semaphore just for
view update read-before-writes. With the new semaphore, even if there are many view
update read-before-writes, they will be queued on a different semaphore than the user
reads, and they won't impact their latency.

The second issue fixed by this patch is the concurrency of the view updates that is
currently unlimited. Because of that view updates may take up so much memory that
they we may run out of memory.

This is fixed by using the read admission on the view update concurrency semaphore.
This limits the number of concurrent view update reads to
max_count_concurrent_view_update_reads, all other incoming view update reads are
queued using just a small chunk of memory. Without this, the reads would also get
queued after exceeding view_update_reader_concurrency_semaphore_serialize_limit_multiplier,
but they would take much more memory while staying in the queue.

The new semaphore has half the capacity of the regular user read concurrency semahpore
and is currently used only for user writes - is't used independently of the scheduling
group on which we base the read semaphore selection, but we use a different code path
for streaming (not database::do_apply) and we shouldn't have view updates in system
writes or during compaction.

Fixes https://github.com/scylladb/scylladb/issues/8873
Fixes https://github.com/scylladb/scylladb/issues/15805
2024-10-21 11:02:06 +02:00
Avi Kivity
c3be2489ce treewide: drop includes of <boost/range/adaptors.hpp>
This includes way too much, including <boost/regex.hpp>, which is huge.
Drop includes of adaptors.hpp and replace by what is needed.

Closes scylladb/scylladb#21187
2024-10-20 17:17:11 +03:00
Botond Dénes
568b767ec3 Merge 'schema: convert from boost ranges to std ranges' from Avi Kivity
To reduce dependency load, change uses of boost ranges to std::ranges.

The first patch is preparation, replacing a construct that isn't easy to support with std ranges with something simpler.

No backport as this is a code cleanup.

Closes scylladb/scylladb#21122

* github.com:scylladb/scylladb:
  schema: replace boost ranges with std ranges
  schema: precompute all_columns_in_select_order()
2024-10-18 08:42:50 +03:00
Avi Kivity
d58cd262ca interval: change boost ranges to std ranges
Reduce dependency load.

size_estimates_virtual_reader is adjusted due to poor boost ranges
and std ranges interoperability.
2024-10-16 13:21:43 +03:00
Avi Kivity
3a75efd6d4 size_estimates_virtual_reader: make virtual_row_iterator more conforming
To work with std::ranges, an iterator has to have a default constructor,
and be assignable. Add the default constructor and convert references
to pointers to support this.
2024-10-16 13:21:25 +03:00
Avi Kivity
820509026f schema: replace boost ranges with std ranges
To reduce dependency load, use std ranges instead of boost ranges.

The std::ranges::{lower,upper}_bound don't support heterogeneous lookup,
but a more natural solution is to use a projection to search for the name,
so we use that and the custom comparator is removed.

Many callers are converted as well due to poor interoperability between
boost ranges and std ranges.
2024-10-15 16:42:54 +03:00
Avi Kivity
db14a01901 Merge 'Use table id as system.sstables partition key' from Pavel Emelyanov
The system.sstables (a.k.a. sstables registry) primary key is "string location" as partition key and "uuid generation" as clustering one. The "location" part was taken from table.config.datadir value which, in turn, a string containing path to on-disk files if the table was located locally, e.g. /var/lib/scylla/data/ks/cf-abc123 one. Recently [1] the datadir was moved from table config onto storage options, but this string is still used as registry key.

Other than being owned by a table with ID, sstables are accessed by restore-from-object-storage code [2]. To make it work, both storage driver and sstable_directory helper class maintain two formats of object prefixes for sstables components. For S3-backed sstables having a record in registry, the path used is s3://bucket/generation/component. For restore code there are user-provided prefixes that do not match the aforementioned pattern. The selection between those two is now made by checking sstable state, which is not obvious and may cause troubles for tiered storage driver.

This patch changes  the registry schema so that partition key becomes "uuid owner" and is set to be table.id() value. This is to stop using the local path by S3 backed sstables. Also this change makes it possible for storage driver and sstable directory to rely on the storage options only to tell different bucket prefixes formats from each other.

As a side effect, the make_s3_object_name() helper, that generates the proper object name, becomes explicit for restore-from-S3 usage. Now it relies on the sstable::filename() calling this->prefix() behind the scenes and the latter to return the user-provided prefix, which is pretty fragile construction.

No need to backport (and it's not going to be easy to do it), storage options feature is still experimental

Refs #20675 [1]
Refs #20305 [2]

Closes scylladb/scylladb#20998

* github.com:scylladb/scylladb:
  sstables: Flatten S3 object name making
  sstable_directory: Flatten directory lister creation
  treewide: Rename sstable registry location field to be owner
  system_keyspace: Change sstables registry partition key type
  sstables: Keep location variant on s3 backend too
  storage_options: Use variant on S3 options
  sstables: Split sstable::filename() helper
  sstables: Add s3_storage::owner() helper
2024-10-13 20:08:43 +03:00
Kamil Braun
96070bb5b3 Merge 'storage_proxy: Add conditions checking to avoid UB in speculating read executors.' from Sergey Zolotukhin
During the investigation of scylladb/scylladb#20282, it was discovered that implementations of speculating read executors have undefined behavior when called with an incorrect number of read replicas. This PR introduces two levels of condition checking:

- Condition checking in speculating read executors for the number of replicas.
- Checking the consistency of the Effective Replication Map in  filter_for_query(): the map is considered incorrect if the list  of replicas contains a node from a data center whose replication factor is 0.

 Please note: This PR does not fix the issue found in scylladb/scylladb#20282;   it only adds condition checks to prevent undefined behavior in cases of  inconsistent inputs.

Refs scylladb/scylladb#20625

As this issue applies to the releases versions and can affect clients, we need backports to 6.0, 6.1, 6.2.

Closes scylladb/scylladb#20851

* github.com:scylladb/scylladb:
  Add conditions checking for get_read_executor
  Avoid an extra call to block_for in db::filter_for_query.
  Improve code readability in consistency_level.cc and storage_proxy.cc
  tools: Add build_info header with functions providing build type information
  tests: Add tests for alter table with RF=1 to RF=0
2024-10-11 15:02:02 +02:00