Zoltan Borok-Nagy has posted comments on this change. ( http://gerrit.cloudera.org:8080/17387 )
Change subject: IMPALA-10681: [WIP] Fix join cardinality if one side is scalar ...................................................................... Patch Set 1: Thanks for the reply Aman. I wonder if we assume uniform distribution of values, and the RHS's cardinality is less than or equal to the LHS's NDV then does it matter if there are duplications on the right side? E.g. lets assume the followings: LHS cardinality is 1000 LHS NDV is 10 RHS cardinality is 5 RHS NDV is unknown If RHS has 5 distinct values, then the selectivity of it is 50%, so the JOIN's output cardinality should be 500. If RHS has the same value 5 times, then the selectivity is 10%, but the multiplication factor is 5x, so the JOIN's output cardinality should be again 500. -- To view, visit http://gerrit.cloudera.org:8080/17387 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: Impala-ASF Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: I8aa9d3b8f3c4848b3e9414fe19ad7ad348d12ecc Gerrit-Change-Number: 17387 Gerrit-PatchSet: 1 Gerrit-Owner: Aman Sinha <amsi...@cloudera.com> Gerrit-Reviewer: Aman Sinha <amsi...@cloudera.com> Gerrit-Reviewer: Impala Public Jenkins <impala-public-jenk...@cloudera.com> Gerrit-Reviewer: Zoltan Borok-Nagy <borokna...@cloudera.com> Gerrit-Comment-Date: Mon, 10 May 2021 12:40:58 +0000 Gerrit-HasComments: No
