From: | "Jouneau Luc" <Luc(dot)Jouneau(at)diamant(dot)jouy(dot)inra(dot)fr> |
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To: | <pgsql-admin(at)postgresql(dot)org> |
Subject: | Re: Seq scan with a like operator |
Date: | 2004-07-23 15:24:31 |
Message-ID: | 011e01c470c9$26b637f0$4703668a@pc502jlo |
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Thread: | |
Lists: | pgsql-admin |
> LIKE requires a different kind of index. See
> <http://www.postgresql.org/docs/7.4/static/indexes-opclass.html>.
Thanks for the answer peter,
I didn't notice it when I red the doc, but if I create the index as
specified then it is the query with equal operator which use a seq scan.
Do I have to create 2 indexes on the same column (with different datatype)
in order to support different kind of queries ?
Well, It seems quite strange to me :
Suppose you have an user interface in which user can parameter his query on
4 varchar fields (independantly, i.e field 4 does not need to have field 1,2
or 3 filled), and you allow to use generic character such as '*' or '?'
(which will be translated into '%' and '_'). User can also fill in exact
values.
Then you would have to create 4*2=8 indexes to handle every combinations of
possible queries.
It would also mean that support both exact generic queries double the
indexing task on update/insert/delete.
Am I wrong ?
Luc Jouneau
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