Cherry pick #95072 to 25.12: Fix crash in getTopKMarks when limit is zero#95086
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robot-clickhouse-ci-2 merged 2 commits intobackport/25.12/95072from Jan 25, 2026
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When `LIMIT -0.` (or any expression that evaluates to 0) is used with `use_skip_indexes_for_top_k = 1`, the `getTopKMarks` functions would call `queue.top()` on an empty priority queue, causing undefined behavior and a segmentation fault. The fix adds an early return when `n == 0` in both `getTopKMarks` overloads, since requesting the top 0 elements should return nothing. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Fix crash in `getTopKMarks` when limit is zero
577a386
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backport/25.12/95072
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Original pull-request #95072
Do not merge this PR manually
This pull-request is a first step of an automated backporting.
It contains changes similar to calling
git cherry-picklocally.If you intend to continue backporting the changes, then resolve all conflicts if any.
Otherwise, if you do not want to backport them, then just close this pull-request.
The check results does not matter at this step - you can safely ignore them.
Troubleshooting
If the conflicts were resolved in a wrong way
If this cherry-pick PR is completely screwed by a wrong conflicts resolution, and you want to recreate it:
pr-cherrypicklabel from the PRYou also need to check the Original pull-request for
pr-backports-createdlabel, and delete if it's presented thereThe PR source
The PR is created in the CI job