feat: Combine low selectivity vectors generated by the hash join filter #11739
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I ran the fuzzer test with join filters applied for half an hour. |
…cebookincubator#10987) Summary: Combine low selectivity vectors generated by join filter **Problem** We found in TPCDS query72 that the join filter leads to a large number of low-selectivity result vectors, which affects the performance of subsequent operations. Details: The number of input vectors on the probe side of the corresponding join is 84,087, with a total of 743,851,486 rows (our batch size is set to 10,240). Due to a large number of duplicate rows on the build side, the final result inflates. The number of output vectors from the join is 2,806,054. The corresponding join filter filters out a large portion of the results, so the number of output rows is 1,430,253,235. This leads to the output of many sparse vectors (the average batch row count is 504). **Solution** The original logic continues the [loop](https://github.com/facebookincubator/velox/blob/main/velox/exec/HashProbe.cpp#L1065) to fill more rows if no rows pass the filters. To resolve this issue, we can extend it to handle cases where only partial rows pass the filters. We need to ensure that the indices 'outputRowMapping_' and 'outputTableRows_' are filled as much as possible until we either reach the preferred batch size or have processed all rows in the current input vector. This approach will not only address the issue mentioned above but also avoid unnecessary data copying. Pull Request resolved: facebookincubator#10987 Reviewed By: pedroerp Differential Revision: D65949331 Pulled By: Yuhta fbshipit-source-id: e8e54e7be1b5a93ba71387aa49f00dcff3cc8aa2
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This PR re-applies #10987, addressing the following issues:
preferredOutputBatchBytes.