Am Dienstag, 29. November 2005 10:05 schrieb Mario Weilguni:
> Hello Tom,
>
> I tried both patches on a different machine (but had to take the patches
> from cvs diff, cut'n paste from the mail-program did not work). Up until
> now, they work like a charm, correct results and fast. I will try on th
ql-hackers@postgresql.org
Subject: Re: Hashjoin startup strategy (was Re: [HACKERS] Getting different
number of results when using hashjoin on/off)
I wrote:
> For a query like this, where the hash join is being done repeatedly,
> it might be useful for the executor itself to track how often each
&g
Tom Lane <[EMAIL PROTECTED]> writes:
> In particular, the executor knows that the outer subplan is parameterless
> and therefore should deliver the same results each time (modulo volatile
> functions of course), so after the first cycle it could know that there's no
> point in trying the early fe
Greg Stark <[EMAIL PROTECTED]> writes:
> I suspect this is obvious but since you asked, there isn't any way to keep
> around the hash table and just reuse it repeatedly instead of having to rescan
> the data over and over is there?
We already do that when possible --- which it's not in the particu
I wrote:
> For a query like this, where the hash join is being done repeatedly,
> it might be useful for the executor itself to track how often each
> subplan has been seen to be empty.
I implemented a simple form of this, and it made 8.1 faster than 8.0
on the test case I was using. Give it a tr
Title: AW: Hashjoin startup strategy (was Re: [HACKERS] Getting different number of results when using hashjoin on/off)
If the query runs slow it will be not such a problem, but I was very concerned about other queries having this problem too - without knowing it. I've already rewritte
"Mario Weilguni" <[EMAIL PROTECTED]> writes:
> Thanks for the quick response, I've tried the patch, but it did not work
> as expected. When I set enable_hashjoin to off, everything works as
> expected, but with hashjoin on I do not even get results anymore, CPU is
> going up to 100% and after 3 min
