executor: do not reorder handles when building requests for IndexMergeJoin
#20138
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I don't know why |
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LGTM |
ti-srebot
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Sep 22, 2020
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Your auto merge job has been accepted, waiting for:
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/run-all-tests |
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@qw4990 merge failed. |
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/merge |
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Your auto merge job has been accepted, waiting for:
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/run-all-tests |
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@qw4990 merge failed. |
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/run-all-tests |
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Signed-off-by: ti-srebot <ti-srebot@pingcap.com>
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cherry pick to release-4.0 in PR #20147 |
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What problem does this PR solve?
Issue Number: close #20137
Problem Summary: executor: do not reorder handles when building requests for
IndexMergeJoinWhat is changed and how it works?
Reordering handles when building requests is for merging successive handles into one, for example
h in (2, 3, 1)can be merged to(h>=1 and h<=3), which may improve the performance.But some handles may overflow, after reordering, they cannot keep the original order.
IndexMergeJoinrequires all rows returned in a specific order, so reordering handles may break this.To avoid this risk, do not reorder handles when building requests for
IndexMergeJoin.Check List
Tests
Release note
IndexMergeJoin