Re: Hash join in 8.3 - Mailing list pgsql-general

From Tom Lane
Subject Re: Hash join in 8.3
Date
Msg-id 17340.1197569957@sss.pgh.pa.us
Whole thread Raw
In response to Hash join in 8.3  (André Volpato<andre.volpato@ecomtecnologia.com.br>)
List pgsql-general
=?ISO-8859-1?Q?Andr=E9_Volpato?= <andre.volpato@ecomtecnologia.com.br> writes:
> Besides the (expected) weak guess on rows for both servers on seq scan
> on jtest, there is something nasty with [2] that prevents the planner to
> use the index.

There isn't anything "preventing" either version from choosing any of
the three plans, as you can easily prove for yourself by experimenting
with enable_nestloop/enable_mergejoin/enable_hashjoin.  The cost
estimates seem close enough that random variations in ANALYZE stats
would change which one looks cheapest.

            regards, tom lane

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