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Fwd: Updates on large tables are extremely slow

From: Yves Vindevogel <yves(dot)vindevogel(at)implements(dot)be>
To: pgsql-performance(at)postgresql(dot)org
Subject: Fwd: Updates on large tables are extremely slow
Date: 2005-06-13 15:49:47
Message-ID: 6243ad910c02150d526b7b32d4cfef9d@implements.be (view raw or flat)
Thread:
Lists: pgsql-performance
I forgot cc

Begin forwarded message:

> From: Yves Vindevogel <yves(dot)vindevogel(at)implements(dot)be>
> Date: Mon 13 Jun 2005 17:45:19 CEST
> To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
> Subject: Re: [PERFORM] Updates on large tables are extremely slow
>
> Yes, but if I update one column, why should PG update 21 indexes ?
> There's only one index affected !
>
> On 13 Jun 2005, at 16:32, Tom Lane wrote:
>
>> Yves Vindevogel <yves(dot)vindevogel(at)implements(dot)be> writes:
>>> rvponp=3D# vacuum verbose tblPrintjobs ;
>>> INFO:  vacuuming "public.tblprintjobs"
>>> [ twenty-one different indexes on one table ]
>>
>> Well, there's your problem.  You think updating all those indexes is
>> free?  It's *expensive*.  Heed the manual's advice: avoid creating
>> indexes you are not certain you need for identifiable commonly-used
>> queries.
>>
>> (The reason delete is fast is it doesn't have to touch the indexes ...
>> the necessary work is left to be done by VACUUM.)
>>
>> 			regards, tom lane
>>
>>
> Met vriendelijke groeten,
> Bien à vous,
> Kind regards,
>
> Yves Vindevogel
> Implements
>

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Next:From: Richard HuxtonDate: 2005-06-13 16:02:24
Subject: Re: Fwd: Updates on large tables are extremely slow
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Subject: Re: Index ot being used

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