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Re: Very specialised query

From: Matthew Wakeling <matthew(at)flymine(dot)org>
To: Віталій Тимчишин <tivv00(at)gmail(dot)com>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Very specialised query
Date: 2009-03-30 16:22:15
Message-ID: (view raw, whole thread or download thread mbox)
Lists: 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 

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


 Jadzia: Don't forget the 34th rule of acquisition: Peace is good for business.
 Quark:  That's the 35th.
 Jadzia: Oh yes, that's right. What's the 34th again?
 Quark:  War is good for business. It's easy to get them mixed up.

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Subject: Re: Forcing seq_scan off for large table joined with tiny table yeilds improved performance
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Subject: Re: Very specialised query

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