Am Freitag, 23. Juli 2004 14:50 schrieb Jouneau Luc:
LIKE requires a different kind of index. See
<http://www.postgresql.org/docs/7.4/static/indexes-opclass.html>.

--
Peter Eisentraut
http://developer.postgresql.org/~petere/

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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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Am Freitag, 23. Juli 2004 17:24 schrieb Jouneau Luc:
Yes.

I think that kind of interface would use the LIKE operator no matter whether
the user entered wildcards or not.

Well, if you want to optimize lots of different queries, the system needs to
provide lots of different support.

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Peter Eisentraut
http://developer.postgresql.org/~petere/

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