Re: Sorting performance vs. MySQL

From: Frank Heikens <frankheikens(at)mac(dot)com>
To: Yang Zhang <yanghatespam(at)gmail(dot)com>
Cc: Alban Hertroys <dalroi(at)solfertje(dot)student(dot)utwente(dot)nl>, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>, pgsql-general(at)postgresql(dot)org
Subject: Re: Sorting performance vs. MySQL
Date: 2010-02-22 19:41:29
Message-ID: 475A81B1-52E6-4DAE-B72B-142B0E3464F7@mac.com
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Op 22 feb 2010, om 20:28 heeft Yang Zhang het volgende geschreven:
>
>
>>
>>
>>>> If your work-mem is too low there's a good chance that Postgres
>>>> has to
>>>> use your disks for sorting, which will obviously be quite slow.
>>>
>>> Relative to the non-terminating 80-minute-so-far sort, Unix sort
>>> runs
>>> much faster (on the order of several minutes).
>>
>> Make sure your index does fit into memory, what's the size of the
>> index?
>
> How might I find out the size and whether it's being fit in memory?

SELECT pg_size_pretty(pg_relation_size('i_transactionid'));

> --
> Yang Zhang
> http://www.mit.edu/~y_z/
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Frank Heikens

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