Re: calculated expressions and index use

Yes, you are right. It was an issue reated to the type compatibility. My
braindead script created tables with 'datetime' types, what is
'timestamp without time zone' after I switched to 'timestamp', all works
fine.

Thanks a loc, the fact, you ensured me, that the constant expression
should be recognized, pushed me much further.

Thanks again

Have a nice day

Pavel

Tom Lane wrote:
> Pavel Hlavnicka <pavel(at)gingerall(dot)cz> writes:
>
>>I use 7.2.1. :(
>
>
> 7.2 certainly will fold "'now'::timestamp - '1 hour'::interval" to a
> timestamp constant. This could be a datatype compatibility issue
> (is created_at the same type? in particular, with/without time zone?)
> or it could be a selectivity issue --- ie, the planner might think the
> condition covers too much of the table to make the index useful.
>
> It would be useful to look at the results of EXPLAIN ANALYZE for this
> query, with and without ENABLE_SEQSCAN turned off.
>
> regards, tom lane

--
Pavel Hlavnicka
Ginger Alliance
www.gingerall.com