Re: Problem (bug?) with like - Mailing list pgsql-general

From Tom Lane
Subject Re: Problem (bug?) with like
Date
Msg-id 2874.1007495539@sss.pgh.pa.us
Whole thread Raw
In response to Re: Problem (bug?) with like  (Bruce Momjian <pgman@candle.pha.pa.us>)
Responses Re: Problem (bug?) with like  (Bruce Momjian <pgman@candle.pha.pa.us>)
Re: Problem (bug?) with like  (Bruce Momjian <pgman@candle.pha.pa.us>)
Re: Problem (bug?) with like  (Bruce Momjian <pgman@candle.pha.pa.us>)
List pgsql-general
Bruce Momjian <pgman@candle.pha.pa.us> writes:
> But what about '%A%' vs. '%AC%'.  Seems the second is reasonably
> different from the first the our optimizer may be fine with that.  Is it
> only when the strings get longer that we lose specificity?

Yeah, I don't think that the estimates are bad for one or two
characters.  But the estimate gets real small real fast as you
increase the number of match characters in the LIKE pattern.
We need to slow that down some.

            regards, tom lane

pgsql-general by date:

Previous
From: "Paul Laub"
Date:
Subject: Re: BEGIN, ROLLBACK,COMMIT
Next
From: Kirk Strauser
Date:
Subject: Grant blanket permissions on a database