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Performance tuning advice for SSI.
Kevin Grittner, with additional wordsmithing by me.
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doc/src/sgml/mvcc.sgml

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@@ -658,6 +658,26 @@ ERROR: could not serialize access due to read/write dependencies among transact
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protections automatically provided by Serializable transactions.
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</para>
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</listitem>
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<listitem>
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<para>
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When the system is forced to combine multiple page-level predicate
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locks into a single relation-level predicate lock because the predicate
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lock table is short of memory, an increase in the rate of serialization
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failures may occur. You can avoid this by increasing
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<xref linkend="guc-max-pred-locks-per-transaction">.
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</para>
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</listitem>
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<listitem>
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<para>
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A sequential scan will always necessitate a relation-level predicate
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lock. This can result in an increased rate of serialization failures.
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It may be helpful to encourage the use of index scans by reducing
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<xref linkend="guc-random-page-cost"> and/or increasing
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<xref linkend="guc-cpu-tuple-cost">. Be sure to weigh any decrease
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in transaction rollbacks and restarts against any overall change in
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query execution time.
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</para>
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</listitem>
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</itemizedlist>
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</para>
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