diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/config.sgml | 24 |
1 files changed, 23 insertions, 1 deletions
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index 30ca1c219c9..05996b49108 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -1,4 +1,4 @@ -<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.162 2008/01/27 19:12:28 tgl Exp $ --> +<!-- $PostgreSQL: pgsql/doc/src/sgml/config.sgml,v 1.163 2008/01/30 18:35:55 tgl Exp $ --> <chapter Id="runtime-config"> <title>Server Configuration</title> @@ -4611,6 +4611,28 @@ dynamic_library_path = 'C:\tools\postgresql;H:\my_project\lib;$libdir' </listitem> </varlistentry> + <varlistentry id="guc-synchronize-seqscans" xreflabel="synchronize_seqscans"> + <term><varname>synchronize_seqscans</varname> (<type>boolean</type>)</term> + <indexterm> + <primary><varname>synchronize_seqscans</> configuration parameter</primary> + </indexterm> + <listitem> + <para> + This allows sequential scans of large tables to synchronize with each + other, so that concurrent scans read the same block at about the + same time and hence share the I/O workload. When this is enabled, + a scan might start in the middle of the table and then <quote>wrap + around</> the end to cover all rows, so as to synchronize with the + activity of scans already in progress. This can result in + unpredictable changes in the row ordering returned by queries that + have no <literal>ORDER BY</> clause. Setting this parameter to + <literal>off</> ensures the pre-8.3 behavior in which a sequential + scan always starts from the beginning of the table. The default + is <literal>on</>. + </para> + </listitem> + </varlistentry> + </variablelist> </sect2> |