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| author | Robert Haas <rhaas@postgresql.org> | 2011-06-21 21:54:36 -0400 |
|---|---|---|
| committer | Robert Haas <rhaas@postgresql.org> | 2011-06-21 21:54:36 -0400 |
| commit | 771a9f69f70e0b4fa95347df7ab346e5bdbc85f2 (patch) | |
| tree | 5439572629e1cc048d4c82d45fea895a9813a10f | |
| parent | a3290f655e12f43943bdabc9fd91477316af24a7 (diff) | |
| download | postgresql-771a9f69f70e0b4fa95347df7ab346e5bdbc85f2.tar.gz postgresql-771a9f69f70e0b4fa95347df7ab346e5bdbc85f2.zip | |
Performance tuning advice for SSI.
Kevin Grittner, with additional wordsmithing by me.
| -rw-r--r-- | doc/src/sgml/mvcc.sgml | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/doc/src/sgml/mvcc.sgml b/doc/src/sgml/mvcc.sgml index e688176acb4..1d337b80550 100644 --- a/doc/src/sgml/mvcc.sgml +++ b/doc/src/sgml/mvcc.sgml @@ -658,6 +658,26 @@ ERROR: could not serialize access due to read/write dependencies among transact protections automatically provided by Serializable transactions. </para> </listitem> + <listitem> + <para> + When the system is forced to combine multiple page-level predicate + locks into a single relation-level predicate lock because the predicate + lock table is short of memory, an increase in the rate of serialization + failures may occur. You can avoid this by increasing + <xref linkend="guc-max-pred-locks-per-transaction">. + </para> + </listitem> + <listitem> + <para> + A sequential scan will always necessitate a relation-level predicate + lock. This can result in an increased rate of serialization failures. + It may be helpful to encourage the use of index scans by reducing + <xref linkend="guc-random-page-cost"> and/or increasing + <xref linkend="guc-cpu-tuple-cost">. Be sure to weigh any decrease + in transaction rollbacks and restarts against any overall change in + query execution time. + </para> + </listitem> </itemizedlist> </para> |