Tim Armstrong has posted comments on this change. Change subject: IMPALA-2581: LIMIT can be propagated down into some aggregations ......................................................................
Patch Set 1: (2 comments) http://gerrit.cloudera.org:8080/#/c/3822/1/be/src/exec/partitioned-aggregation-node.cc File be/src/exec/partitioned-aggregation-node.cc: PS1, Line 506: ReachedLimit > Where do you think that documentation would be most useful? Probably in the header with max_groups_. I think we should also add a DCHECK below: limit_ == -1 || num_rows_returned_ <= limit_ Same with the streaming case. Line 519: Status PartitionedAggregationNode::GetRowsStreaming(RuntimeState* state, > When you say "why THE explicit limit check isn't necessary" [emphasis mine] Yep exactly. Before this change it didn't need a limit check because the planner never applied limits to streaming aggregations. After this change it's less obviously correct. -- To view, visit http://gerrit.cloudera.org:8080/3822 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-MessageType: comment Gerrit-Change-Id: I59c5b7af7a73ccdbc5496b28eacb9b6859d202bc Gerrit-PatchSet: 1 Gerrit-Project: Impala-ASF Gerrit-Branch: master Gerrit-Owner: Jim Apple <[email protected]> Gerrit-Reviewer: Alex Behm <[email protected]> Gerrit-Reviewer: Jim Apple <[email protected]> Gerrit-Reviewer: Matthew Jacobs <[email protected]> Gerrit-Reviewer: Tim Armstrong <[email protected]> Gerrit-HasComments: Yes
