Csaba Ringhofer has posted comments on this change. ( http://gerrit.cloudera.org:8080/12172 )
Change subject: IMPALA-7979: Enhance decoders to support value-skipping ...................................................................... Patch Set 4: Code-Review+1 (2 comments) http://gerrit.cloudera.org:8080/#/c/12172/4/be/src/util/rle-test.cc File be/src/util/rle-test.cc: http://gerrit.cloudera.org:8080/#/c/12172/4/be/src/util/rle-test.cc@191 PS4, Line 191: values Is it really useful to print the values? At this point the same length + bit_width will lead to the same values, so printing values.size() would be enough to reproduce the issue. If the values will also become random, then a seed value could be printed. http://gerrit.cloudera.org:8080/#/c/12172/4/be/src/util/rle-test.cc@275 PS4, Line 275: MakeSequenceBitWidth It would make sense to do this randomly too, but I am leaning towards creating a follow up Jira, which would also deal with adding benchmarks for value skipping to benchmarks/rle-benchmark.cc I do not want to hold up the page index efforts with this, but I am curios about the performance of skipping vs materializing for different selectivity ratios. About a possible implementation: A seed value could be added as parameter, and runs could be added with random [1, max_run_length] length until total length is reached. A similar implementation already exists in benchmarks/rle-benchmark.cc FillWithRle(). -- To view, visit http://gerrit.cloudera.org:8080/12172 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: Impala-ASF Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: Ib848f1bd71735fe84e8064daf700417b32589f57 Gerrit-Change-Number: 12172 Gerrit-PatchSet: 4 Gerrit-Owner: Zoltan Borok-Nagy <[email protected]> Gerrit-Reviewer: Csaba Ringhofer <[email protected]> Gerrit-Reviewer: Impala Public Jenkins <[email protected]> Gerrit-Reviewer: Tim Armstrong <[email protected]> Gerrit-Reviewer: Zoltan Borok-Nagy <[email protected]> Gerrit-Comment-Date: Mon, 21 Jan 2019 10:56:14 +0000 Gerrit-HasComments: Yes
