Re: [GENERAL] 8.2.4 serious slowdown

From: Sim Zacks <sim(at)compulab.co.il>
Date: Fri Jan 11 2008 - 02:39:41 EST

I changed it to "where f.commited is not true" and the query now takes 1 second as opposed to 60. (much faster then the 3 seconds it took on 8.0.1, which could also be because of the coalesce there) Is it considered better practice (or more efficient) to always use (x is not or x=value) instead of coalesce? Or does it make more sense to turn on the option "transform_null_equals"?

Thank you much
Sim

> I assume that the original query is something along the lines of
>
> d left join f on (...) where coalesce(f.commited, false) = false
>
>
> In the meantime, Sim would probably have better luck if he restructured
> this particular clause in some other way, say
>
> where f.commited is not true
> or
> where f.commited = false or f.commited is null
>
> Note also that he really ought to move up to 8.2.6, as 8.2.4 is not
> very sane about what IS NULL means for a left join's result.
>
> regards, tom lane
>
> ---------------------------(end of broadcast)---------------------------
> TIP 6: explain analyze is your friend
>

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TIP 5: don't forget to increase your free space map settings Received on Fri Jan 11 02:57:17 2008