Tianyi Wang has posted comments on this change. Change subject: IMPALA-4794: Grouping distinct agg plan robust to data skew ......................................................................
Patch Set 4: (5 comments) http://gerrit.cloudera.org:8080/#/c/7643/3//COMMIT_MSG Commit Message: Line 11: plan partitions data between phase-1 and phase-2 by the grouping exprs. > the grouping exprs Done Line 12: Under this strategy the data skewness on the grouping exprs directly > make this statement about skew a separate sentence Done Line 13: impacts performance. The new plan partitions data by both the grouping > by both the grouping and distinct agg exprs Done Line 14: exprs and distinct agg exprs, then adds one more aggregation and > Try to avoid descriptions like "supposed to be". We should test and underst Done Line 19: sufficient coverage. The pattern is that the distinct agg exprs are > the first exchange node Done -- To view, visit http://gerrit.cloudera.org:8080/7643 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-MessageType: comment Gerrit-Change-Id: I7bdada0e328b555900c7b7ff8aabc8eb15ae8fa9 Gerrit-PatchSet: 4 Gerrit-Project: Impala-ASF Gerrit-Branch: master Gerrit-Owner: Tianyi Wang <tw...@cloudera.com> Gerrit-Reviewer: Alex Behm <alex.b...@cloudera.com> Gerrit-Reviewer: Tianyi Wang <tw...@cloudera.com> Gerrit-HasComments: Yes
