Re: [SQL] calculated expressions and index use

[Pavel Hlavnicka]

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 <[EMAIL PROTECTED]> 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


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