Large update and disk usage - Mailing list pgsql-novice

From Steve Horn
Subject Large update and disk usage
Date
Msg-id CAFLkBaXTcF=vi=MoCKf1_qn03QRjwCjvP1GBc_rX6wd2zOBCdg@mail.gmail.com
Whole thread Raw
Responses Re: Large update and disk usage  (Andreas Kretschmer <akretschmer@spamfence.net>)
List pgsql-novice
(Postgres 9.1 on CentOS)

Performing an update to two columns on a table with 40 million records, all in one transaction.

The size of the table on disk (according to pg_relation_size) is 131GB. My question is: when an update to all of these rows is performed, how much disk space should I provision? 

Also would be nice to understand how Postgres physically handles large updates like this. (Does it create a temporary or global temporary table, and then drop it when the transaction is committed?)

--
Steve Horn

pgsql-novice by date:

Previous
From: Stephen Cook
Date:
Subject: Re: Service start up error "The Service name is invalid net helpmsg 2185"
Next
From: Andreas Kretschmer
Date:
Subject: Re: Large update and disk usage