Re: Seq scan with a like operator

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

Yes.

> 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.

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

> It would also mean that support both exact generic queries double the
> indexing task on update/insert/delete.

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

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