From: Chris <dmagick@gmail.com>
To: Tobias Brox <tobias@nordicbet.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Defining performance.
Date: Fri, 01 Dec 2006 14:32:05 +1100
Message-ID: <456FA235.1070406@gmail.com> (raw)
In-Reply-To: <20061201011554.GA27123@oppetid.no>
References: <20061201011554.GA27123@oppetid.no>
Tobias Brox wrote:
> [nospam@hardgeus.com - Thu at 06:37:12PM -0600]
>> As my dataset has gotten larger I have had to throw more metal at the
>> problem, but I have also had to rethink my table and query design. Just
>> because your data set grows linearly does NOT mean that the performance of
>> your query is guaranteed to grow linearly! A sloppy query that runs OK
>> with 3000 rows in your table may choke horribly when you hit 50000.
>
> Then some limit is hit ... either the memory cache, or that the planner
> is doing an unlucky change of strategy when hitting 50000.
Not really. A bad query is a bad query (eg missing a join element). It
won't show up for 3000 rows, but will very quickly if you increase that
by a reasonable amount. Even as simple as a missing index on a join
column won't show up for a small dataset but will for a larger one.
It's a pretty common mistake to assume that a small dataset will behave
exactly the same as a larger one - not always the case.
--
Postgresql & php tutorials
http://www.designmagick.com/
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To: pgsql-performance@postgresql.org
Cc: dmagick@gmail.com, tobias@nordicbet.com
Subject: Re: Defining performance.
In-Reply-To: <456FA235.1070406@gmail.com>
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