Re: 7.3 vs 7.2 - different query plan, bad performance - Mailing list pgsql-performance

From Tom Lane
Subject Re: 7.3 vs 7.2 - different query plan, bad performance
Date
Msg-id 2680.1055773063@sss.pgh.pa.us
Whole thread Raw
In response to Re: 7.3 vs 7.2 - different query plan, bad performance  (Ryszard Lach <siaco@autograf.pl>)
List pgsql-performance
Ryszard Lach <siaco@autograf.pl> writes:
> The point is, that my tables (and queries) are a 'little' bit more
> complicated and I wanted to give as simple example as I could. I think
> that problem is that subselects are _much_slower_ executed in 7.3 than
> in 7.2, just as someone already wrote here.

No, the problem is that 7.3 fails to notice that it doesn't really need
to execute the subselect at all.  This is the price we paid for being
sure that a post-release bug fix wouldn't break anything more serious.
There is a better fix in place for 7.4.

            regards, tom lane

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