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Re: WAL logging volume and CREATE TABLE

From: Bruce Momjian <bruce(at)momjian(dot)us>
To: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
Cc: Robert Haas <robertmhaas(at)gmail(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: WAL logging volume and CREATE TABLE
Date: 2011-08-03 18:52:01
Message-ID: 201108031852.p73Iq1h23402@momjian.us (view raw or flat)
Thread:
Lists: pgsql-hackers
Alvaro Herrera wrote:
> Excerpts from Bruce Momjian's message of mar ago 02 22:46:55 -0400 2011:
> 
> > I have created a documentation patch to clarify this, and to mention
> > CREATE TABLE AS which also has this optimization.
> 
> It doesn't seem particularly better to me.  How about something like
> 
> In minimal level, WAL-logging of some operations can be safely skipped,
> which can make those operations much faster (see <blah>).  Operations on
> which this optimization can be applied include: 
> <simplelist>
>  <item>CREATE INDEX</item>
>  <item>CLUSTER</item>
>  <item>CREATE TABLE AS</item>
>  <item>COPY, when tables that were created or truncated in the same
>  transaction
> </simplelist>
> 
> Minimal WAL does not contain enough information to reconstruct the data
> from a base backup and the WAL logs, so either <literal>archive</> or
> <literal>hot_standby</> level must be used to enable ...

Good idea --- updated patch attached.

-- 
  Bruce Momjian  <bruce(at)momjian(dot)us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + It's impossible for everything to be true. +

Attachment: /pgpatches/wal_level
Description: text/x-diff (1.7 KB)

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