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In documentaiton, clarify which commands have reduced WAL volume for

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wal_level = minimum.

Backpatch to 9.1 and 9.0.
This commit is contained in:
Bruce Momjian 2011-08-04 12:06:53 -04:00
parent 4af43ee3f1
commit 38de5aad54
1 changed files with 12 additions and 5 deletions
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doc/src/sgml/config.sgml
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@ -1451,11 +1451,18 @@ SET ENABLE_SEQSCAN TO OFF;
This parameter can only be set at server start. This parameter can only be set at server start.
</para> </para>
<para> <para>
In <literal>minimal</> level, WAL-logging of some bulk operations, like In <literal>minimal</> level, WAL-logging of some bulk
<command>CREATE INDEX</>, <command>CLUSTER</> and <command>COPY</> on operations can be safely skipped, which can make those
a table that was created or truncated in the same transaction can be operations much faster (see <xref linkend="populate-pitr">).
safely skipped, which can make those operations much faster (see Operations in which this optimization can be applied include:
<xref linkend="populate-pitr">). But minimal WAL does not contain <simplelist>
<item>CREATE TABLE AS</item>
<item>CREATE INDEX</item>
<item>CLUSTER</item>
<item>COPY into tables that were created or truncated in the same
transaction
</simplelist>
But minimal WAL does not contain
enough information to reconstruct the data from a base backup and the enough information to reconstruct the data from a base backup and the
WAL logs, so either <literal>archive</> or <literal>hot_standby</> WAL logs, so either <literal>archive</> or <literal>hot_standby</>
level must be used to enable level must be used to enable