Re: [HACKERS] Re: [GENERAL] big bad join problems - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: [HACKERS] Re: [GENERAL] big bad join problems
Date
Msg-id 199902020338.WAA11337@candle.pha.pa.us
Whole thread Raw
In response to Re: [HACKERS] Re: [GENERAL] big bad join problems  (Vadim Mikheev <vadim@krs.ru>)
List pgsql-hackers
> > > Yes, it was me. I don't object against 6, but just remember that
> > > there were other people having troubles with GEQO and this is
> > > why table count was increased from 6 to 8.
> > 
> > Do you remember what problems?
> 
> No. Either the same as now (long planning) or bad plans
> (long execution).

My rememberance was that GEQO was slower for some 6-table joins, so it
was recommended to keep it at 8.  Tom clearly is on the proper track in
checking the number of indexes when using GEQO.  That should allow us to
set a proper value that will use GEQO in most/all cases.

--  Bruce Momjian                        |  http://www.op.net/~candle maillist@candle.pha.pa.us            |  (610)
853-3000+  If your life is a hard drive,     |  830 Blythe Avenue +  Christ can be your backup.        |  Drexel Hill,
Pennsylvania19026
 


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