| From: | Alvaro Herrera <alvherre(at)commandprompt(dot)com> |
|---|---|
| To: | Heikki Linnakangas <heikki(at)enterprisedb(dot)com> |
| Cc: | Teodor Sigaev <teodor(at)sigaev(dot)ru>, Patches <pgsql-patches(at)postgresql(dot)org> |
| Subject: | Re: Partial match in GIN |
| Date: | 2008-04-08 19:19:53 |
| Message-ID: | 20080408191953.GN9062@alvh.no-ip.org |
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| Lists: | pgsql-patches |
Heikki Linnakangas wrote:
> Teodor Sigaev wrote:
>> GIN speeds up '%foo%' too - which is impossible for btree. But I don't
>> like a hack around LIKE support in BTree. This support uses outflank
>> ways missing regular one.
>
> You could satisfy '%foo%' using a regular and a reverse B-tree index,
> and a bitmap AND. Which is interestingly similar to the way you proposed
> to use a TIDBitmap within GIN.
Huh, can you? I can see doing "col LIKE 'foo%' OR reverse(col) LIKE
reverse('%foo')" with two btree indexes, but not a true %foo% ...
--
Alvaro Herrera http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support
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