From: Pavel Hlavnicka <pavel@gingerall.cz>
To: pgsql-sql@postgresql.org
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Subject: Re: calculated expressions and index use
Date: Fri, 31 Jan 2003 17:03:21 +0100
Message-ID: <3E3A9E49.1090503@gingerall.cz> (raw)
In-Reply-To: <8577.1044024965@sss.pgh.pa.us>
References: <3E394AA6.8080400@gingerall.cz>
<20100.1043945485@sss.pgh.pa.us>
<3E3A3757.3040906@gingerall.cz>
<8577.1044024965@sss.pgh.pa.us>
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@gingerall.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
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To: pgsql-sql@postgresql.org
Cc: pavel@gingerall.cz, tgl@sss.pgh.pa.us
Subject: Re: calculated expressions and index use
In-Reply-To: <3E3A9E49.1090503@gingerall.cz>
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