Hi, Thanks for your reply. I will go through the link. By the way my hive version is 0.12
Thanks, Harsha On Fri, Apr 17, 2015 at 4:16 AM, Lefty Leverenz <leftylever...@gmail.com> wrote: > 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 >> > >
