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Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/config.sgml | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index 48d7939d2de..46bc31de4c4 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -5951,6 +5951,12 @@ local0.* /var/log/postgresql </para> <para> + This overrides <xref linkend="guc-log-min-duration-sample"/>, + meaning that queries with duration exceeding this setting are not + subject to sampling and are always logged. + </para> + + <para> For clients using extended query protocol, durations of the Parse, Bind, and Execute steps are logged independently. </para> @@ -5972,6 +5978,85 @@ local0.* /var/log/postgresql </listitem> </varlistentry> + <varlistentry id="guc-log-min-duration-sample" xreflabel="log_min_duration_sample"> + <term><varname>log_min_duration_sample</varname> (<type>integer</type>) + <indexterm> + <primary><varname>log_min_duration_sample</varname> configuration parameter</primary> + </indexterm> + </term> + <listitem> + <para> + Allows to sample the logging of the duration of each completed + statement if the statement ran for at least the specified amount of + time. If this value is specified without units, it is taken as milliseconds. + Setting this to zero samples all statement durations. + Minus-one (the default) disables sampling statement durations. + For example, if you set it to <literal>250ms</literal> + then all SQL statements that run 250ms or longer will be considered + for sampling, with sample rate is controlled by <xref linkend="guc-log-statement-sample-rate"/>. + Enabling this parameter can be helpful when the traffic too high to + sample all queries. + Only superusers can change this setting. + </para> + + <para> + This option has lower priority than <xref linkend="guc-log-min-duration-statement"/>, + meaning that statements with durations exceeding <xref linkend="guc-log-min-duration-statement"/> + are not subject to sampling and are always logged. + </para> + + <para> + For clients using extended query protocol, durations of the Parse, + Bind, and Execute steps are logged independently. + </para> + + <note> + <para> + When using this option together with + <xref linkend="guc-log-statement"/>, + the text of statements that are logged because of + <varname>log_statement</varname> will not be repeated in the + duration log message. + If you are not using <application>syslog</application>, it is recommended + that you log the PID or session ID using + <xref linkend="guc-log-line-prefix"/> + so that you can link the statement message to the later + duration message using the process ID or session ID. + </para> + </note> + </listitem> + </varlistentry> + + <varlistentry id="guc-log-statement-sample-rate" xreflabel="log_statement_sample_rate"> + <term><varname>log_statement_sample_rate</varname> (<type>real</type>) + <indexterm> + <primary><varname>log_statement_sample_rate</varname> configuration parameter</primary> + </indexterm> + </term> + <listitem> + <para> + Determines the fraction of statements with duration exceeding + <xref linkend="guc-log-min-duration-sample"/> to be logged. + This is a statistical parameter, for example <literal>0.5</literal> + means there is statistically one in two chances to log the statement. + The default is <literal>1.0</literal>, meaning log all such + statements. + Setting this to zero disables sampling logging, same as setting + <varname>log_min_duration_sample</varname> to + <literal>-1</literal>. + <varname>log_statement_sample_rate</varname> is helpful when the + traffic is too high to log all queries. + Only superusers can change this setting. + </para> + <note> + <para> + Like all statement-logging options, this option can add significant + overhead. + </para> + </note> + </listitem> + </varlistentry> + <varlistentry id="guc-log-transaction-sample-rate" xreflabel="log_transaction_sample_rate"> <term><varname>log_transaction_sample_rate</varname> (<type>real</type>) <indexterm> |