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Document the DEFERRABLE option in SET TRANSACTION command.
Kevin Grittner
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@ -135,6 +135,17 @@ SET SESSION CHARACTERISTICS AS TRANSACTION <replaceable class="parameter">transa
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among those listed. This is a high-level notion of read-only that
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does not prevent all writes to disk.
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</para>
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<para>
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The <literal>DEFERRABLE</literal> transaction property has no effect
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unless the transaction is also <literal>SERIALIZABLE</literal> and
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<literal>READ ONLY</literal>. When all of these properties are set on a
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transaction, the transaction may block when first acquiring its snapshot,
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after which it is able to run without the normal overhead of a
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<literal>SERIALIZABLE</literal> transaction and without any risk of
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contributing to or being cancelled by a serialization failure. This mode
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is well suited for long-running reports or backups.
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</para>
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</refsect1>
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<refsect1>
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