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Document the DEFERRABLE option in SET TRANSACTION command. 

Kevin Grittner
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Heikki Linnakangas 2011-03-07 10:42:49 +02:00
parent 97e3dacd84
commit faba108fe4
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doc/src/sgml/ref/set_transaction.sgml
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@ -135,6 +135,17 @@ SET SESSION CHARACTERISTICS AS TRANSACTION <replaceable class="parameter">transa
among those listed. This is a high-level notion of read-only that
does not prevent all writes to disk.
</para>
<para>
The <literal>DEFERRABLE</literal> transaction property has no effect
unless the transaction is also <literal>SERIALIZABLE</literal> and
<literal>READ ONLY</literal>. When all of these properties are set on a
transaction, the transaction may block when first acquiring its snapshot,
after which it is able to run without the normal overhead of a
<literal>SERIALIZABLE</literal> transaction and without any risk of
contributing to or being cancelled by a serialization failure. This mode
is well suited for long-running reports or backups.
</para>
</refsect1>
<refsect1>