Re: Performance UPDATE/INSERT - Mailing list pgsql-general

From A. Kretschmer
Subject Re: Performance UPDATE/INSERT
Date
Msg-id 20060411102756.GF5520@webserv.wug-glas.de
Whole thread Raw
In response to Re: Performance UPDATE/INSERT  (Alban Hertroys <alban@magproductions.nl>)
List pgsql-general
am  11.04.2006, um 12:15:41 +0200 mailte Alban Hertroys folgendes:
> MG wrote:
> >I have to improve the performance of the UPDATES and I was wondering why
> >the UPDATEs need twice as long as the INSERTs.
>
> IIRC, an UPDATE is a DELETE/INSERT combo. That's because the original
> record still needs to be visible to other existing transactions (because of
> MVCC). You can't change its data but need to create a new record instead
> and mark the original as obsolete.

Correctly, and thats why we need VACUUM to clean the space on the disk.


HTH, Andreas
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