Re: Mnogosearch (Was: Re: website doc search is ... ) - Mailing list pgsql-general

From Tom Lane
Subject Re: Mnogosearch (Was: Re: website doc search is ... )
Date
Msg-id 29300.1072984670@sss.pgh.pa.us
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In response to Re: Mnogosearch (Was: Re: website doc search is ... )  ("Marc G. Fournier" <scrappy@postgresql.org>)
Responses Re: Mnogosearch (Was: Re: website doc search is ... )
List pgsql-general
"Marc G. Fournier" <scrappy@postgresql.org> writes:
> I don't see a difference between the two, other then time changes, but
> that could just be that runA had a server a bit more idle then runB ...
> something I'm not seeing here?

Well, the difference I was hoping for was a more accurate rows estimate
for the indexscan, which indeed we got (estimate went from 3210 to
16075, vs reality of 15533).  But it didn't change the plan :-(.

Looking more closely, I see the rows estimate for the seqscan on "url"
is pretty awful too (1968 vs reality of 304811).  I think it would get
better if you were doing just
    AND (url.url LIKE 'http://archives.postgresql.org/%%');
without the concatenation of an empty string.  Is there a reason for the
concatenation part of the expression?

            regards, tom lane

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