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List:       postgresql-general
Subject:    Re: [GENERAL] Questions about update, delete, ctid...
From:       DANTE Alexandra <Alexandra.Dante () bull ! net>
Date:       2006-07-31 15:00:55
Message-ID: 44CE1B27.1090705 () bull ! net
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Hello Tom, Martijn and List,

Thank you for yours answers !
This point is now closed for me and I can go further in the mecanisms of 
VACUUM.

Regards,
Alexandra


Tom Lane wrote:

>DANTE Alexandra <Alexandra.Dante@bull.net> writes:
>  
>
>>    - during a SELECT query on a tuple just updated and commited, does 
>>the executor first detect the old tuple and then via the c_tid link go 
>>to the new version of the tuple ? or go directly to the new version ?
>>    
>>
>
>Neither.  SELECT doesn't care about update relationships, it just
>returns whatever row version is current according to its snapshot.
>It's only UPDATE/DELETE that are constrained to act on the most
>current version of each row.
>
>			regards, tom lane
>
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