Aman Sinha has posted comments on this change. ( http://gerrit.cloudera.org:8080/16723 )
Change subject: IMPALA-10314: Optimize planning time for simple limits ...................................................................... Patch Set 11: > Patch Set 11: > > (4 comments) > > > Patch Set 11: > > > > (4 comments) > > > > Just a couple corner cases I have run into; given this is an opt-in > > optimization now it might not be incorrect to ignore these. > > > > I think it's good to think about the case where this optimization helps and > > not risk an incorrect limit in other cases. Where this helps most. > > a. lots of files > > b. small limits > > > > a) the scan range and scheduling overhead is only slow when there are many > > hosts + files. > > > > b) for large limits maybe the bulk of query run time goes to fetching > > results and not the planning, but that said it may not hurt too much in > > this case. > > Thanks for the comments. I will create a follow-up JIRA to address couple of > these comments considering that this CR was +2 ed. > Note that the more generalized issue of optimizing for limits is something > that Tim and I had some offline discussion about and he created > 'IMPALA-10347: Explore approaches to optimizing queries that will likely be > short-circuited by limits' Created https://issues.apache.org/jira/browse/IMPALA-10353 -- To view, visit http://gerrit.cloudera.org:8080/16723 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: Impala-ASF Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: I9d6a79263bc092e0f3e9a1d72da5618f3cc35574 Gerrit-Change-Number: 16723 Gerrit-PatchSet: 11 Gerrit-Owner: Aman Sinha <[email protected]> Gerrit-Reviewer: Aman Sinha <[email protected]> Gerrit-Reviewer: Impala Public Jenkins <[email protected]> Gerrit-Reviewer: Qifan Chen <[email protected]> Gerrit-Reviewer: Shant Hovsepian <[email protected]> Gerrit-Reviewer: Tim Armstrong <[email protected]> Gerrit-Comment-Date: Tue, 24 Nov 2020 02:37:12 +0000 Gerrit-HasComments: No
