[SPARK-21644][SQL] LocalLimit.maxRows is defined incorrectly #18851
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cc @JoshRosen |
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Test build #80275 has finished for PR 18851 at commit
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| * In most cases when we want to push down limit, it is often better to only push some partition | ||
| * local limit. Consider the following: | ||
| * | ||
| * GlobalLimit(Union(A, B) |
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Missing ')' at the end: GlobalLimit(Union(A, B) -> GlobalLimit(Union(A, B)).
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Looks like the strip global limit is used by at least some test cases. |
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retest this please |
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Test build #82285 has finished for PR 18851 at commit
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What changes were proposed in this pull request?
The definition of
maxRowsinLocalLimitoperator was simply wrong. This patch introduces a newmaxRowsPerPartitionmethod and uses that in pruning. The patch also adds more documentation on why we need local limit vs global limit.Note that this previously has never been a bug because the way the code is structured, but future use of the maxRows could lead to bugs.
How was this patch tested?
Should be covered by existing test cases.