Fix quantilesGK bug

[taiyang-li]

Changelog category (leave one):

• Bug Fix (user-visible misbehavior in an official stable release)

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

Fix quantilesGK bug, close #57683

[robot-clickhouse]

This is an automated comment for commit a89890b with description of existing statuses. It's updated for the latest CI running

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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
ClickBench	Runs [ClickBench](https://github.com/ClickHouse/ClickBench/) with instant-attach table	✅ success
ClickHouse build check	Builds ClickHouse in various configurations for use in further steps. You have to fix the builds that fail. Build logs often has enough information to fix the error, but you might have to reproduce the failure locally. The cmake options can be found in the build log, grepping for cmake. Use these options and follow the general build process	✅ success
Compatibility check	Checks that clickhouse binary runs on distributions with old libc versions. If it fails, ask a maintainer for help	✅ success
Docker server and keeper images	There's no description for the check yet, please add it to tests/ci/ci_config.py:CHECK_DESCRIPTIONS	✅ success
Docs check	There's no description for the check yet, please add it to tests/ci/ci_config.py:CHECK_DESCRIPTIONS	✅ success
Fast tests	There's no description for the check yet, please add it to tests/ci/ci_config.py:CHECK_DESCRIPTIONS	✅ 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. Integrational 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
Integration tests	The integration tests report. In parenthesis the package type is given, and in square brackets are the optional part/total tests	✅ success
Mergeable Check	Checks if all other necessary checks are successful	✅ 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
SQLancer	Fuzzing tests that detect logical bugs with SQLancer tool	✅ success
Sqllogic	Run clickhouse on the sqllogic test set against sqlite and checks that all statements are passed	✅ 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
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Unit tests	Runs the unit tests for different release types	✅ success

Check name	Description	Status
CI running	A meta-check that indicates the running CI. Normally, it's in success or pending state. The failed status indicates some problems with the PR	⏳ pending
Stress test	Runs stateless functional tests concurrently from several clients to detect concurrency-related errors	❌ failure
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	❌ failure

[alexey-milovidov]

Let's take a look at Fast Test.

[alexey-milovidov]

The code is not memory-safe: there is double-free: https://s3.amazonaws.com/clickhouse-test-reports/58216/d168dae7d1fca79903fe96f10f1711a349bacfb5/fuzzer_astfuzzerasan/report.html

When you will fix it, also add the example from Fuzzer as a new test.

[taiyang-li]

The code is not memory-safe: there is double-free: https://s3.amazonaws.com/clickhouse-test-reports/58216/d168dae7d1fca79903fe96f10f1711a349bacfb5/fuzzer_astfuzzerasan/report.html

When you will fix it, also add the example from Fuzzer as a new test.

I'm really confused about how to find the sql which caused crash. Need you help, thanks

[alexey-milovidov]

It should be near the end at server.log.zst

[taiyang-li]

It should be near the end at server.log.zst

@alexey-milovidov fixed, hope for your review and merge

[alexey-milovidov]

Ok. Looks perfect. Can we make a functional test for this?
Otherwise, it complains: "Bugfix validate check — Changed tests don't reproduce the bug "

[taiyang-li]

Ok. Looks perfect. Can we make a functional test for this?
Otherwise, it complains: "Bugfix validate check — Changed tests don't reproduce the bug "

it was already added in tests/queries/0_stateless/02661_quantile_approx.sql. It is strange why it still complains @alexey-milovidov

[Algunenano]

The failures are unrelated. Please update with master so they go away.

And have a look at this comment. Let's add a sanity check so we don't reserve too much memory on corrupted input (which a client might send maliciously).

[Algunenano]

Some comments about the PR:

• As a bugfix, this PR is bad. A whole refactor means that a) the PR is 100x what it needed to be (5 vs 500 lines), b) it takes longer to be reviewed and c) you get a full review and d) it won't be backported.
• I don't like moving code from .cpp to .h just to add an example that doesn't provide any value. For testing you can simply include the .cpp (#include <AggregateFunctions/AggregateFunctionQuantileGK.cpp>) and do whatever local tests you require. No need to add new headers that will be misused and grow the compilation and binary size.
• I'd recommend you to clean up the commits before making a PR. Having commits adding prints or commenting and uncommenting code is bad as it will show you as the last person changing the code, although you left it exactly as it was.

[taiyang-li]

Some comments about the PR:

• As a bugfix, this PR is bad. A whole refactor means that a) the PR is 100x what it needed to be (5 vs 500 lines), b) it takes longer to be reviewed and c) you get a full review and d) it won't be backported.
• I don't like moving code from .cpp to .h just to add an example that doesn't provide any value. For testing you can simply include the .cpp (#include <AggregateFunctions/AggregateFunctionQuantileGK.cpp>) and do whatever local tests you require. No need to add new headers that will be misused and grow the compilation and binary size.
• I'd recommend you to clean up the commits before making a PR. Having commits adding prints or commenting and uncommenting code is bad as it will show you as the last person changing the code, although you left it exactly as it was.

Good advices. I'll make this PR clean.