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Re: Query only slow on first run

From: cluster <skrald(at)amossen(dot)dk>
To: pgsql-performance(at)postgresql(dot)org
Subject: Re: Query only slow on first run
Date: 2007-11-28 20:16:08
Message-ID: fikia6$26ql$ (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
>> I'm wondering why --- doesn't seem like it should take 6400msec to fetch
>> 646 rows, unless perhaps the data is just horribly misordered relative
>> to the index.   Which may in fact be the case ...

Hmm, actually I still don't understand why it takes 6400 ms to fetch the 
rows. As far as I can see the index used is "covering" so that real row 
lookups shouldn't be necessary. Also, only the the random_numbers 
induces by questions with status = 1 should be considered - and this 
part is a relatively small subset.

In general, I don't understand why the query is so I/O dependant as it 
apparently is.

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Subject: Re: Query only slow on first run
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