Re: Very specialised query - Mailing list pgsql-performance

From Matthew Wakeling
Subject Re: Very specialised query
Date
Msg-id alpine.DEB.2.00.0903301719230.21772@aragorn.flymine.org
Whole thread Raw
In response to Very specialised query  (Matthew Wakeling <matthew@flymine.org>)
Responses Re: Very specialised query
List pgsql-performance
On Mon, 30 Mar 2009, Віталій Тимчишин wrote:
> select
> case when n == 1 then id1 else id2 end,
> case when n == 2 then id1 else id2 end
>
> from (
>    ... a, (values (1),(2)) b(n)

Yeah, that's nice.

However, it is still the case that we can't trust the database to choose
the correct plan. It is currently only choosing the correct plan now by
chance, and some time later it may by chance switch to one that takes 40
minutes.

I'll certainly add it to my list of possibilities.

Matthew

--
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 Quark:  War is good for business. It's easy to get them mixed up.

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