| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> |
| Cc: | drheart(at)wanadoo(dot)es, Lista PostgreSql <pgsql-general(at)postgresql(dot)org>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Problem (bug?) with like |
| Date: | 2001-12-04 19:52:19 |
| Message-ID: | 2874.1007495539@sss.pgh.pa.us |
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| Lists: | pgsql-general pgsql-hackers |
Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)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
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