From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
---|---|
To: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
Cc: | Jann Röder <roederja(at)ethz(dot)ch>, pgsql-performance <pgsql-performance(at)postgresql(dot)org> |
Subject: | Re: Inefficient query plan |
Date: | 2010-08-23 15:20:55 |
Message-ID: | 21464.1282576855@sss.pgh.pa.us |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-performance |
Alvaro Herrera <alvherre(at)commandprompt(dot)com> writes:
> Hmm, I'm placing bets on the bpchar weirdness. I'd try getting rid of
> that and using plain varchar for all the columns.
That's certainly what's inhibiting it from considering an indexscan
on the larger table. I'm not as convinced as the OP that a nestloop
indexscan is really going to win compared to the hash plan, but if
the comparison value is varchar then an index on a bpchar column
is simply not useful --- at least not unless you stick an explicit
cast into the query, so that the comparison will have bpchar rather
than varchar semantics.
regards, tom lane
From | Date | Subject | |
---|---|---|---|
Next Message | gnuoytr | 2010-08-23 15:22:46 | Re: Inefficient query plan |
Previous Message | Kevin Grittner | 2010-08-23 15:03:11 | Re: Inefficient query plan |