Harsha, that document is from 2010. What version of Hive are you using? Here's some up-to-date information in the Hive wiki: Join Optimimzation <https://cwiki.apache.org/confluence/display/Hive/LanguageManual+JoinOptimization> .
-- Lefty On Thu, Apr 16, 2015 at 2:38 AM, Harsha HN <99harsha.h....@gmail.com> wrote: > Hi All, > > I went through below mentioned Facebook engineering page, > https://www.facebook.com/notes/facebook-engineering/join > -optimization-in-apache-hive/470667928919 > > I set following for auto conversion of joins, > set hive.auto.convert.join=true; > set hive.mapjoin.smalltable.filesize=1000000000; (1GB) > > I observed some queries performed 2X faster in MAP JOIN as opposed to > Common join > and also instances where MAP JOIN is 3X slower than Common Join. > > Any thoughts on what might be slowing down MAP JOIN in some cases ? > > I have 40 Node cluster, so I have huge RAM available. > > Thanks, > Harsha >
