Re: Major upgrade advice

Jan-Ivar Mellingen <jan-ivar(dot)mellingen(at)alreg(dot)no> writes:
> I got curious and did a few tests on a 8.3.3 database on my laptop.
> The 3 different queries all worked, but one took twice as long.

> SELECT * FROM alarmlogg WHERE alarm_tid >= CAST('2007-05-20' as
> timestamp) AND alarm_tid < CAST('2008-05-21' as timestamp);
> --> 301 seconds.

Unsurprising: a comparison between a timestamp with timezone and
one without involves a timezone conversion, so it's gonna be slow.

It's a bit annoying that the system doesn't have the intelligence
to convert the constants to timestamptz just once; but I think
doing that would require introducing an implicit cast from
timestamp to timestamptz, which might cause surprising behaviors
elsewhere.

regards, tom lane