Alex Behm has posted comments on this change. ( http://gerrit.cloudera.org:8080/7999 )
Change subject: [DOCS] Tighten up advice about first COMPUTE INCREMENTAL STATS ...................................................................... Patch Set 2: (4 comments) http://gerrit.cloudera.org:8080/#/c/7999/2/docs/shared/impala_common.xml File docs/shared/impala_common.xml: http://gerrit.cloudera.org:8080/#/c/7999/2/docs/shared/impala_common.xml@1228 PS2, Line 1228: DROP STATS</codeph> and : <codeph>DROP INCREMENTAL STATS</codeph>) > are these drops required? They are not required if you *exactly* what you are doing, but that does not apply to most people. Dropping first is always safe and definitely the recommended practice. If you do not drop and switch back-and-forth between compute stats and compute incremental sats, then you may end up with "unexpected" table metadata. http://gerrit.cloudera.org:8080/#/c/7999/2/docs/shared/impala_common.xml@1243 PS2, Line 1243: be cached on every <cmdname>impalad</cmdname> host. If this metadata for a table exceeds > more specifically, impalads that are also coordinators? Yes http://gerrit.cloudera.org:8080/#/c/7999/2/docs/shared/impala_common.xml@1243 PS2, Line 1243: metadata for a table exceeds : 2 GB > is there a diagnostic page that we can point to here that explains how to f This is a longer story. I asked Bharath to help here. http://gerrit.cloudera.org:8080/#/c/7999/2/docs/shared/impala_common.xml@1247 PS2, Line 1247: does not affect > does that mean lack of stats has not affect on optimization or something el Please see my explanation on what "incremental" stats is in previous patch sets. Dropping *incremental* stats has no effect on the row counts and NDVs used in query optimization. -- To view, visit http://gerrit.cloudera.org:8080/7999 To unsubscribe, visit http://gerrit.cloudera.org:8080/settings Gerrit-Project: Impala-ASF Gerrit-Branch: master Gerrit-MessageType: comment Gerrit-Change-Id: Ia53a6518ce5541e5c9a2cd896856ce042a599b03 Gerrit-Change-Number: 7999 Gerrit-PatchSet: 2 Gerrit-Owner: John Russell <[email protected]> Gerrit-Reviewer: Alex Behm <[email protected]> Gerrit-Reviewer: Greg Rahn <[email protected]> Gerrit-Reviewer: John Russell <[email protected]> Gerrit-Reviewer: Mostafa Mokhtar <[email protected]> Gerrit-Reviewer: Silvius Rus <[email protected]> Gerrit-Reviewer: Vuk Ercegovac <[email protected]> Gerrit-Comment-Date: Fri, 06 Oct 2017 17:34:31 +0000 Gerrit-HasComments: Yes
