Re: Query 200x slower on server [PART 2] - Mailing list pgsql-performance

From Richard Huxton
Subject Re: Query 200x slower on server [PART 2]
Date
Msg-id 44CDCCDF.8000304@archonet.com
Whole thread Raw
In response to Query 200x slower on server [PART 2]  ("NbForYou" <nbforyou@hotmail.com>)
List pgsql-performance
NbForYou wrote:
> See Query 200x slower on server [PART 1] before reading any further

Cant' find it. Sorry.

>
> QUERY PLAN ON MY HOME SERVER
[snip]
> Total runtime: 125.432 ms
>
> This means that the Query is 200 times slower on the webhost!
>
> How can I resolve this?

First - what is different between the two plans and why? PostgreSQL will
be choosing a different plan because:
1. It's estimating different numbers of rows for one or more steps
2. It's estimating a different cost for one or more steps
3. It's triggering the genetic optimiser which means you're not
necessarily going to get the same plan each time.
4. You've got different versions of PG on the different machines.

--
   Richard Huxton
   Archonet Ltd

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