[ https://issues.apache.org/jira/browse/IMPALA-7843?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16752838#comment-16752838 ]
Tim Armstrong commented on IMPALA-7843: --------------------------------------- [~jonapgar] I'm looking at adding an experimental flag to enable mt_dop for all queries: IMPALA-8097. It will initially be a "use at your own risk" flag will come with a bunch of caveats since it will be missing various optimisations, tuning, etc. But this might be of interest to you - it would of course be good to get feedback on it. > MT_DOP should be configurable per subquery > ------------------------------------------ > > Key: IMPALA-7843 > URL: https://issues.apache.org/jira/browse/IMPALA-7843 > Project: IMPALA > Issue Type: Improvement > Reporter: Jon Apgar > Priority: Major > > MT_DOP > 0 will cause queries with JOIN statements to fail, however the > *subqueries* within the main query _might_ otherwise have been able to run > successfully with MT_DOP > 0. > A use-case for subqueries may be to limit the size of complex joins or > eliminate redundant aggregation in the outer query, By allowing MT_DOP > 0 on > subqueries you could significantly speed up the entire query. > MT_DOP is not the only session variable which may be effectively configured > per subquery. Perhaps there should be a way of specifying applicable > variables within the select statement of a query. -- This message was sent by Atlassian JIRA (v7.6.3#76005) --------------------------------------------------------------------- To unsubscribe, e-mail: issues-all-unsubscr...@impala.apache.org For additional commands, e-mail: issues-all-h...@impala.apache.org