Set `max_parallel_replicas` default to `1000` by thevar1able · Pull Request #74504 · ClickHouse/ClickHouse

thevar1able · 2025-01-13T10:17:13Z

Changelog category (leave one):

Improvement

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

Use up to 1000 parallel replicas by default.

CI Settings (Only check the boxes if you know what you are doing)

All builds in Builds_1 and Builds_2 stages are always mandatory
and will run independently of the checks below:

Allow: All Required Checks
Allow: Stateless tests
Allow: Stateful tests
Allow: Integration Tests
Allow: Performance tests
Allow: All Builds
Allow: batch 1, 2 for multi-batch jobs
Allow: batch 3, 4, 5, 6 for multi-batch jobs

Run only fuzzers related jobs (libFuzzer fuzzers, AST fuzzers, BuzzHouse, etc.)
Exclude: AST fuzzers

robot-ch-test-poll4 · 2025-01-13T10:19:38Z

This is an automated comment for commit 29ca3bf with description of existing statuses. It's updated for the latest CI running

❌ Click here to open a full report in a separate page

Check name	Description	Status
Integration tests	The integration tests report. In parenthesis the package type is given, and in square brackets are the optional part/total tests	❌ failure

Successful checks

Check name	Description	Status
AST fuzzer	Runs randomly generated queries to catch program errors. The build type is optionally given in parenthesis. If it fails, ask a maintainer for help	✅ success
Builds	There's no description for the check yet, please add it to tests/ci/ci_config.py:CHECK_DESCRIPTIONS	✅ success
BuzzHouse (asan)	There's no description for the check yet, please add it to tests/ci/ci_config.py:CHECK_DESCRIPTIONS	✅ success
BuzzHouse (msan)	There's no description for the check yet, please add it to tests/ci/ci_config.py:CHECK_DESCRIPTIONS	✅ success
BuzzHouse (tsan)	There's no description for the check yet, please add it to tests/ci/ci_config.py:CHECK_DESCRIPTIONS	✅ success
BuzzHouse (ubsan)	There's no description for the check yet, please add it to tests/ci/ci_config.py:CHECK_DESCRIPTIONS	✅ success
ClickBench	Runs ClickBench with instant-attach table	✅ success
Compatibility check	Checks that clickhouse binary runs on distributions with old libc versions. If it fails, ask a maintainer for help	✅ success
Docker keeper image	The check to build and optionally push the mentioned image to docker hub	✅ success
Docker server image	The check to build and optionally push the mentioned image to docker hub	✅ success
Docs check	Builds and tests the documentation	✅ success
Fast test	Normally this is the first check that is ran for a PR. It builds ClickHouse and runs most of stateless functional tests, omitting some. If it fails, further checks are not started until it is fixed. Look at the report to see which tests fail, then reproduce the failure locally as described here	✅ success
Flaky tests	Checks if new added or modified tests are flaky by running them repeatedly, in parallel, with more randomization. Functional tests are run 100 times with address sanitizer, and additional randomization of thread scheduling. Integration tests are run up to 10 times. If at least once a new test has failed, or was too long, this check will be red. We don't allow flaky tests, read the doc	✅ success
Install packages	Checks that the built packages are installable in a clear environment	✅ success
Performance Comparison	Measure changes in query performance. The performance test report is described in detail here. In square brackets are the optional part/total tests	✅ success
Stateful tests	Runs stateful functional tests for ClickHouse binaries built in various configurations -- release, debug, with sanitizers, etc	✅ success
Stateless tests	Runs stateless functional tests for ClickHouse binaries built in various configurations -- release, debug, with sanitizers, etc	✅ success
Stress test	Runs stateless functional tests concurrently from several clients to detect concurrency-related errors	✅ success
Style check	Runs a set of checks to keep the code style clean. If some of tests failed, see the related log from the report	✅ success
Unit tests	Runs the unit tests for different release types	✅ success
Upgrade check	Runs stress tests on server version from last release and then tries to upgrade it to the version from the PR. It checks if the new server can successfully startup without any errors, crashes or sanitizer asserts	✅ success

src/Storages/StorageDistributed.cpp

thevar1able · 2025-01-23T21:43:06Z

test_storage_s3_queue/test.py::test_alter_settings #73263

devcrafter · 2025-01-27T10:58:19Z

src/Client/HedgedConnections.cpp

          context_->getSettingsRef()[Setting::connections_with_failover_max_tries].value,
          context_->getSettingsRef()[Setting::fallback_to_stale_replicas_for_distributed_queries].value,
-          context_->getSettingsRef()[Setting::max_parallel_replicas].value,
+          context_->getSettingsRef()[Setting::allow_experimental_parallel_reading_from_replicas].value > 0


It doesn't look correct. Parallel replicas and hedged connection are independent. Hedge connections are not used with parallel replicas. So, we should pass here max_parallel_replicas setting as it's.
It means the query will use just 1 replicas for distributed query when parallel replicas is disabled, but parallel replicas and distributed queries are not the same thing.

I wonder how do we get pass tests with such change. Either test doesn't check number of used replicas for a query or ...

I guess I took it wrong, — it should mean 1 replica per shard. So, it should be ok.

devcrafter · 2025-01-27T11:30:40Z

tests/integration/test_hedged_requests_parallel/test.py

    )
    check_query()
-    check_changing_replica_events(4)
+    check_changing_replica_events(3)


Changing max_parallel_replicas shouldn't affect this check. AFAIU, here we introduced delay in response for 4 replicas, so we expect that hedge connection mechanism will try to replace unresponsive replicas with another one (it checks HedgedRequestsChangeReplica profile event). Let's check with the author, @Avogar

thevar1able marked this pull request as draft January 13, 2025 10:17

robot-ch-test-poll4 added the pr-improvement Pull request with some product improvements label Jan 13, 2025

thevar1able mentioned this pull request Jan 13, 2025

Use cluster table functions automatically if parallel replicas are enabled #70659

Merged

21 tasks

nickitat reviewed Jan 13, 2025

View reviewed changes

src/Storages/StorageDistributed.cpp Show resolved Hide resolved

nickitat approved these changes Jan 13, 2025

View reviewed changes

thevar1able force-pushed the 1k-parallel-replicas-by-default branch 3 times, most recently from da63396 to 62903ca Compare January 20, 2025 14:07

thevar1able force-pushed the 1k-parallel-replicas-by-default branch from abb2f81 to 7f7b319 Compare January 23, 2025 08:10

thevar1able added 7 commits January 23, 2025 09:37

Set max_parallel_replicas default to 1000

61e3737

Fix tests with offset setting

3b22c7b

Update test reference

a182d43

Update integration tests

f9d1b8f

Fix one more case of unconditional max_parallel_replica usage

9018cf5

Revert test changes

cdb8614

Fix test

f835bc1

thevar1able force-pushed the 1k-parallel-replicas-by-default branch from 7f7b319 to f835bc1 Compare January 23, 2025 08:38

boop

29ca3bf

thevar1able marked this pull request as ready for review January 23, 2025 21:43

thevar1able added this pull request to the merge queue Jan 23, 2025

alexey-milovidov assigned nickitat Jan 23, 2025

Merged via the queue into master with commit d9184e5 Jan 23, 2025

thevar1able deleted the 1k-parallel-replicas-by-default branch January 23, 2025 22:12

robot-clickhouse added the pr-synced-to-cloud The PR is synced to the cloud repo label Jan 23, 2025

devcrafter reviewed Jan 27, 2025

View reviewed changes

devcrafter mentioned this pull request Jan 28, 2025

test_hedged_requests/test.py::test_combination4 is flaky #75162

Closed

den-crane mentioned this pull request Apr 28, 2025

Duplicates of local replica data with max_replica_delay_for_distributed_queries setting #79638

Closed

This was referenced Aug 20, 2025

SELECT ... FROM Distributed table returns multiple rows instead of single aggregated result #85933

Closed

Unexpected packet from server expected TablesStatusResponse #85961

Closed

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Set `max_parallel_replicas` default to `1000`#74504

Set `max_parallel_replicas` default to `1000`#74504
thevar1able merged 8 commits intomasterfrom
1k-parallel-replicas-by-default

thevar1able commented Jan 13, 2025

Uh oh!

robot-ch-test-poll4 commented Jan 13, 2025 •

edited by robot-ch-test-poll2

Loading

Uh oh!

Uh oh!

thevar1able commented Jan 23, 2025

Uh oh!

devcrafter Jan 27, 2025

Uh oh!

devcrafter Jan 27, 2025

Uh oh!

devcrafter Jan 27, 2025

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

5 participants

Conversation

thevar1able commented Jan 13, 2025

Changelog category (leave one):

Changelog entry (a user-readable short description of the changes that goes to CHANGELOG.md):

CI Settings (Only check the boxes if you know what you are doing)

Uh oh!

robot-ch-test-poll4 commented Jan 13, 2025 • edited by robot-ch-test-poll2 Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Uh oh!

thevar1able commented Jan 23, 2025

Uh oh!

devcrafter Jan 27, 2025

Choose a reason for hiding this comment

Uh oh!

devcrafter Jan 27, 2025

Choose a reason for hiding this comment

Uh oh!

devcrafter Jan 27, 2025

Choose a reason for hiding this comment

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

5 participants

robot-ch-test-poll4 commented Jan 13, 2025 •

edited by robot-ch-test-poll2

Loading