Re: Partial match in GIN - Mailing list pgsql-patches

From Alvaro Herrera
Subject Re: Partial match in GIN
Date
Msg-id 20080408191953.GN9062@alvh.no-ip.org
Whole thread Raw
In response to Re: Partial match in GIN  (Heikki Linnakangas <heikki@enterprisedb.com>)
Responses Re: Partial match in GIN
List 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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