| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | josh(at)agliodbs(dot)com |
| Cc: | "David Olbersen" <DOlbersen(at)stbernard(dot)com>, pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: Help with LIKE |
| Date: | 2003-03-21 02:06:21 |
| Message-ID: | 8915.1048212381@sss.pgh.pa.us |
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| Lists: | pgsql-performance |
Josh Berkus <josh(at)agliodbs(dot)com> writes:
>> SELECT * FROM table WHERE url ~ '^http://.*something.*$';
> That search still requires a seq scan, since it has "gaps" in the seqence of
> characters. That is,
> url ~ '^http://www.something.*' could use an index, but your search above
> cannot.
Actually, it *can* use an index ... but the index condition will only
use the characters before the ".*", ie, "http://". Which is just about
useless if you're searching a column of URLs :-(
I agree that tsearch or OpenFTS are the tools to be looking at.
regards, tom lane
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