Re: Query optimizer & prepared statements

Jack Orenstein wrote:
> If x is an integer column with an index, then
>
>     select ...
>     from T
>     where x > 1
>
> and
>
>     select ...
>     from T
>     where x > 1000000000
>
> could be optimized differently. So how is optimization done for a
> prepared statement containing a variable, e.g.
>
>     select ...
>     from T
>     where x > $1

http://www.postgresql.org/docs/current/static/sql-prepare.html#AEN58703
explains this.

If your parameter is a unique key, then you won't see any difference. If
your parameter is a non-unique key, there may be differences depending
on your data/distribution etc.

--
Postgresql & php tutorials
http://www.designmagick.com/