Re: WAL logging volume and CREATE TABLE

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 ).  Operations on
> which this optimization can be applied include: 
> 
>  CREATE INDEX
>  CLUSTER
>  CREATE TABLE AS
>  COPY, when tables that were created or truncated in the same
>  transaction
> 
> 
> Minimal WAL does not contain enough information to reconstruct the data
> from a base backup and the WAL logs, so either archive</> or
> hot_standby</> level must be used to enable ...

Good idea --- updated patch attached.

-- 
  Bruce Momjian          http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + It's impossible for everything to be true. +
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml
new file mode 100644
index 4fadca9..aac6c3b
*** a/doc/src/sgml/config.sgml
--- b/doc/src/sgml/config.sgml
*************** SET ENABLE_SEQSCAN TO OFF;
*** 1451,1461 ****
          This parameter can only be set at server start.
         
         
!         In minimal</> level, WAL-logging of some bulk operations, like
!         CREATE INDEX</>, CLUSTER</> and COPY</> on
!         a table that was created or truncated in the same transaction can be
!         safely skipped, which can make those operations much faster (see
!         ). But minimal WAL does not contain
          enough information to reconstruct the data from a base backup and the
          WAL logs, so either archive</> or hot_standby</>
          level must be used to enable
--- 1451,1468 ----
          This parameter can only be set at server start.
         
         
!         In minimal</> level, WAL-logging of some bulk
!         operations can be safely skipped, which can make those
!         operations much faster (see ).
!         Operations in which this optimization can be applied include:
!         
!          CREATE INDEX
!          CLUSTER
!          CREATE TABLE AS
!          COPY into tables that were created or truncated in the same
!          transaction
!         
!         But minimal WAL does not contain
          enough information to reconstruct the data from a base backup and the
          WAL logs, so either archive</> or hot_standby</>
          level must be used to enable