[SPARK-58324][SQL] Drop unused sameOrderExpressions from GroupPartitionsExec k-way merge ordering#57503
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…onsExec k-way merge ordering ### What changes were proposed in this pull request? `GroupPartitionsExec` builds a `SortedMergeCoalescedRDD` for the k-way merge and hands it a `LazyCodeGenOrdering` built from `child.outputOrdering`. The generated comparator (`GenerateOrdering`) only needs each `SortOrder`'s sort key (child, direction, null ordering), so this drops `sameOrderExpressions` -- planner-only metadata -- via a small `kWayMergeOrdering` helper before constructing the ordering, so it is not serialized with the RDD in every task. ### Why are the changes needed? `sameOrderExpressions` is unused by the comparator and is unnecessary payload serialized with every task. It was also the vector for the StackOverflowError fixed in SPARK-58323 (an unforced, deeply-nested `LazyList`); not carrying it here removes this operator's exposure to any such ordering entirely (defense-in-depth), independent of that fix. ### Does this PR introduce any user-facing change? No. ### How was this patch tested? New unit test in `GroupPartitionsExecSuite` asserting `kWayMergeOrdering` keeps the sort key but drops `sameOrderExpressions`. Existing SPARK-55715 sorted-merge tests cover comparator correctness. ### Was this patch authored or co-authored using generative AI tooling? Generated-by: Claude Opus 4.8
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LGTM, thanks @peter-toth
uros-b
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…onsExec k-way merge ordering ### What changes were proposed in this pull request? `GroupPartitionsExec` builds a `SortedMergeCoalescedRDD` for the k-way merge and hands it a `LazyCodeGenOrdering` built from `child.outputOrdering`. The generated comparator (`GenerateOrdering`) only needs each `SortOrder`'s sort key (child, direction, null ordering), so this drops `sameOrderExpressions` -- planner-only metadata -- via a small `kWayMergeOrdering` helper before constructing the ordering, so it is not serialized with the RDD in every task. ### Why are the changes needed? `sameOrderExpressions` is unused by the merge comparator and is unnecessary payload serialized with every task. It was also the vector for the `StackOverflowError` fixed in SPARK-58323 (an unforced, deeply-nested `LazyList`); not carrying it here removes this operator's exposure to any such ordering entirely (defense-in-depth), independent of that fix. ### Does this PR introduce _any_ user-facing change? No. ### How was this patch tested? New unit test in `GroupPartitionsExecSuite` asserting `kWayMergeOrdering` keeps the sort key but drops `sameOrderExpressions`. Existing SPARK-55715 sorted-merge tests cover comparator correctness. ### Was this patch authored or co-authored using generative AI tooling? Generated-by: Claude Opus 4.8 Closes #57503 from peter-toth/SPARK-58324-drop-sameorderexpressions-kway-merge. Authored-by: Peter Toth <peter.toth@gmail.com> Signed-off-by: Peter Toth <peter.toth@gmail.com> (cherry picked from commit cce4355) Signed-off-by: Peter Toth <peter.toth@gmail.com>
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…onsExec k-way merge ordering ### What changes were proposed in this pull request? `GroupPartitionsExec` builds a `SortedMergeCoalescedRDD` for the k-way merge and hands it a `LazyCodeGenOrdering` built from `child.outputOrdering`. The generated comparator (`GenerateOrdering`) only needs each `SortOrder`'s sort key (child, direction, null ordering), so this drops `sameOrderExpressions` -- planner-only metadata -- via a small `kWayMergeOrdering` helper before constructing the ordering, so it is not serialized with the RDD in every task. ### Why are the changes needed? `sameOrderExpressions` is unused by the merge comparator and is unnecessary payload serialized with every task. It was also the vector for the `StackOverflowError` fixed in SPARK-58323 (an unforced, deeply-nested `LazyList`); not carrying it here removes this operator's exposure to any such ordering entirely (defense-in-depth), independent of that fix. ### Does this PR introduce _any_ user-facing change? No. ### How was this patch tested? New unit test in `GroupPartitionsExecSuite` asserting `kWayMergeOrdering` keeps the sort key but drops `sameOrderExpressions`. Existing SPARK-55715 sorted-merge tests cover comparator correctness. ### Was this patch authored or co-authored using generative AI tooling? Generated-by: Claude Opus 4.8 Closes #57503 from peter-toth/SPARK-58324-drop-sameorderexpressions-kway-merge. Authored-by: Peter Toth <peter.toth@gmail.com> Signed-off-by: Peter Toth <peter.toth@gmail.com> (cherry picked from commit cce4355) Signed-off-by: Peter Toth <peter.toth@gmail.com>
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Thank you everyone for the review! |
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What changes were proposed in this pull request?
GroupPartitionsExecbuilds aSortedMergeCoalescedRDDfor the k-way merge and hands it aLazyCodeGenOrderingbuilt fromchild.outputOrdering. The generated comparator (GenerateOrdering) only needs eachSortOrder's sort key (child, direction, null ordering), so this dropssameOrderExpressions-- planner-only metadata -- via a smallkWayMergeOrderinghelper before constructing the ordering, so it is not serialized with the RDD in every task.Why are the changes needed?
sameOrderExpressionsis unused by the merge comparator and is unnecessary payload serialized with every task. It was also the vector for theStackOverflowErrorfixed in SPARK-58323 (an unforced, deeply-nestedLazyList); not carrying it here removes this operator's exposure to any such ordering entirely (defense-in-depth), independent of that fix.Does this PR introduce any user-facing change?
No.
How was this patch tested?
New unit test in
GroupPartitionsExecSuiteassertingkWayMergeOrderingkeeps the sort key but dropssameOrderExpressions. Existing SPARK-55715 sorted-merge tests cover comparator correctness.Was this patch authored or co-authored using generative AI tooling?
Generated-by: Claude Opus 4.8