Tim Armstrong has posted comments on this change. ( http://gerrit.cloudera.org:8080/14846 )
Change subject: IMPALA-9195: Using multithreaded execution to accelerate 'show tables/databases' ...................................................................... Patch Set 1: (1 comment) http://gerrit.cloudera.org:8080/#/c/14846/1//COMMIT_MSG Commit Message: http://gerrit.cloudera.org:8080/#/c/14846/1//COMMIT_MSG@14 PS1, Line 14: This patch enables MT_DOP query option to accelerate 'show tables/databases' Let's not overload mt_dop. mt_dop should only be about query execution, not metadata loading. On a side node, I'm not sure whether a query option is the right place to control this. For other metadata operations we use fixed-size thread pools for the most part. The problem with having parallelism per-operation is that you don't have any control over the amount of load induced on the underlying metadata systems. There's also nothing to stop end-users from setting it to an absurd value. Anyway, I'll let reviewers figure out what would be best there, my main point was please don't use mt_dop for this, we want to reserve that for the backend. -- To view, visit http://gerrit.cloudera.org:8080/14846 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: Impala-ASF Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: I860e0d18afa0421665f8b3b1c5561d6bdacc5e96 Gerrit-Change-Number: 14846 Gerrit-PatchSet: 1 Gerrit-Owner: Zhou Xu <peter.cose....@gmail.com> Gerrit-Reviewer: Impala Public Jenkins <impala-public-jenk...@cloudera.com> Gerrit-Reviewer: Quanlong Huang <huangquanl...@gmail.com> Gerrit-Reviewer: Tim Armstrong <tarmstr...@cloudera.com> Gerrit-Reviewer: Vihang Karajgaonkar <vih...@cloudera.com> Gerrit-Comment-Date: Fri, 06 Dec 2019 17:08:55 +0000 Gerrit-HasComments: Yes
