Re: Analyze using savepoints?

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От Alvaro Herrera Munoz
Тема Re: Analyze using savepoints?
Дата
Msg-id 20040809130125.GA19105@dcc.uchile.cl
обсуждение исходный текст
Ответ на Analyze using savepoints?  (Christopher Kings-Lynne <chriskl@familyhealth.com.au>)
Ответы Re: Analyze using savepoints?  (Tom Lane <tgl@sss.pgh.pa.us>)
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On Mon, Aug 09, 2004 at 04:44:58PM +0800, Christopher Kings-Lynne wrote:
> I read this in the release notes:
> 
> ---
> # Database-wide ANALYZE does not hold locks across tables (Tom)
> 
> This reduces the potential for deadlocks against other backends that 
> want exclusive locks on tables. To get the benefit of this change, do 
> not execute database-wide ANALYZE inside a transaction block (BEGIN 
> block); it must be able to commit and start a new transaction for each 
> table.
> ---
> 
> Does that mean that now if we used savepoints internally, analyze can 
> still be run in a transaction and still not hold lots of locks?

No, because savepoints do not release locks on successful completion, only
on rollback.

I think both VACUUM and ANALYZE could be best served by appropiate use
of short-lived ResourceOwners.  It needs some thought though.

-- 
Alvaro Herrera (<alvherre[@]dcc.uchile.cl>)
"El realista sabe lo que quiere; el idealista quiere lo que sabe" (Anónimo)


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