Re: Regex query not using index - Mailing list pgsql-general

From Postgres User
Subject Re: Regex query not using index
Date
Msg-id b88c3460802192158g664290e5ka31be94eb48aea69@mail.gmail.com
Whole thread Raw
In response to Re: Regex query not using index  (Chris <dmagick@gmail.com>)
Responses Re: Regex query not using index
List pgsql-general
by the way, your example works fine unless it's a null value or empty string
unfortunately, postgres isn't smart enough to know that the when
p_param below is null, that the WHERE condition can be ignored

select * from table where name in (Coalesce(p_param, name))

which is the same as:   select * from table where name in (name)

postgres does a row scan on the above sql.  too slow.


On Feb 19, 2008 9:34 PM, Chris <dmagick@gmail.com> wrote:
> Postgres User wrote:
> > Yes that works, but the whole point of the exercise is replace many OR
> > statements with 1 regex expression.  So it's not what I'm looking for.
>
> Why do you want it done this way?
>
> You can build an array of strings to check and use an in clause.
>
> Using php :
>
> $checks = array('AA', 'BA');
>
> $query = "select * from table where name in ('" . implode("','",
> $checks) . "')";
>
> and it should use an index (up to a point anyway).
>
> --
>
> Postgresql & php tutorials
> http://www.designmagick.com/
>

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