diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/config.sgml | 32 | ||||
| -rw-r--r-- | doc/src/sgml/monitoring.sgml | 31 | ||||
| -rw-r--r-- | doc/src/sgml/wal.sgml | 4 |
3 files changed, 58 insertions, 9 deletions
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index a8354576108..e55700f35b8 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -8378,9 +8378,11 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv; displayed in <link linkend="monitoring-pg-stat-database-view"> <structname>pg_stat_database</structname></link>, <link linkend="monitoring-pg-stat-io-view"> - <structname>pg_stat_io</structname></link>, in the output of the + <structname>pg_stat_io</structname></link> (if <varname>object</varname> + is not <literal>wal</literal>), in the output of the <link linkend="pg-stat-get-backend-io"> - <function>pg_stat_get_backend_io()</function></link> function, in the + <function>pg_stat_get_backend_io()</function></link> function (if + <varname>object</varname> is not <literal>wal</literal>), in the output of <xref linkend="sql-explain"/> when the <literal>BUFFERS</literal> option is used, in the output of <xref linkend="sql-vacuum"/> when the <literal>VERBOSE</literal> option is used, by autovacuum @@ -8393,6 +8395,32 @@ COPY postgres_log FROM '/full/path/to/logfile.csv' WITH csv; </listitem> </varlistentry> + <varlistentry id="guc-track-wal-io-timing" xreflabel="track_wal_io_timing"> + <term><varname>track_wal_io_timing</varname> (<type>boolean</type>) + <indexterm> + <primary><varname>track_wal_io_timing</varname> configuration parameter</primary> + </indexterm> + </term> + <listitem> + <para> + Enables timing of WAL I/O calls. This parameter is off by default, + as it will repeatedly query the operating system for the current time, + which may cause significant overhead on some platforms. + You can use the <application>pg_test_timing</application> tool to + measure the overhead of timing on your system. + I/O timing information is displayed in + <link linkend="monitoring-pg-stat-io-view"> + <structname>pg_stat_io</structname></link> for the + <varname>object</varname> <literal>wal</literal> and in the output of + the <link linkend="pg-stat-get-backend-io"> + <function>pg_stat_get_backend_io()</function></link> function for the + <varname>object</varname> <literal>wal</literal>. + Only superusers and users with the appropriate <literal>SET</literal> + privilege can change this setting. + </para> + </listitem> + </varlistentry> + <varlistentry id="guc-track-functions" xreflabel="track_functions"> <term><varname>track_functions</varname> (<type>enum</type>) <indexterm> diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml index 3dfd059b7ee..9178f1d34ef 100644 --- a/doc/src/sgml/monitoring.sgml +++ b/doc/src/sgml/monitoring.sgml @@ -184,6 +184,11 @@ postgres 27093 0.0 0.0 30096 2752 ? Ss 11:34 0:00 postgres: ser </para> <para> + The parameter <xref linkend="guc-track-wal-io-timing"/> enables monitoring + of WAL read, write and fsync times. + </para> + + <para> Normally these parameters are set in <filename>postgresql.conf</filename> so that they apply to all server processes, but it is possible to turn them on or off in individual sessions using the <xref @@ -2723,7 +2728,11 @@ description | Waiting for a newly initialized WAL file to reach durable storage </para> <para> Time spent in read operations in milliseconds (if - <xref linkend="guc-track-io-timing"/> is enabled, otherwise zero) + <xref linkend="guc-track-io-timing"/> is enabled and + <varname>object</varname> is not <literal>wal</literal>, + or if <xref linkend="guc-track-wal-io-timing"/> is enabled + and <varname>object</varname> is <literal>wal</literal>, + otherwise zero) </para> </entry> </row> @@ -2757,7 +2766,11 @@ description | Waiting for a newly initialized WAL file to reach durable storage </para> <para> Time spent in write operations in milliseconds (if - <xref linkend="guc-track-io-timing"/> is enabled, otherwise zero) + <xref linkend="guc-track-io-timing"/> is enabled and + <varname>object</varname> is not <literal>wal</literal>, + or if <xref linkend="guc-track-wal-io-timing"/> is enabled + and <varname>object</varname> is <literal>wal</literal>, + otherwise zero) </para> </entry> </row> @@ -2816,8 +2829,12 @@ description | Waiting for a newly initialized WAL file to reach durable storage <structfield>extend_time</structfield> <type>double precision</type> </para> <para> - Time spent in extend operations in milliseconds (if - <xref linkend="guc-track-io-timing"/> is enabled, otherwise zero) + Time spent in extend operations in milliseconds. (if + <xref linkend="guc-track-io-timing"/> is enabled and + <varname>object</varname> is not <literal>wal</literal>, + or if <xref linkend="guc-track-wal-io-timing"/> is enabled + and <varname>object</varname> is <literal>wal</literal>, + otherwise zero) </para> </entry> </row> @@ -2887,7 +2904,11 @@ description | Waiting for a newly initialized WAL file to reach durable storage </para> <para> Time spent in fsync operations in milliseconds (if - <xref linkend="guc-track-io-timing"/> is enabled, otherwise zero) + <xref linkend="guc-track-io-timing"/> is enabled and + <varname>object</varname> is not <literal>wal</literal>, + or if <xref linkend="guc-track-wal-io-timing"/> is enabled + and <varname>object</varname> is <literal>wal</literal>, + otherwise zero) </para> </entry> </row> diff --git a/doc/src/sgml/wal.sgml b/doc/src/sgml/wal.sgml index 4fc09761115..f3b86b26be9 100644 --- a/doc/src/sgml/wal.sgml +++ b/doc/src/sgml/wal.sgml @@ -808,7 +808,7 @@ <para> There are two internal functions to write WAL data to disk: <function>XLogWrite</function> and <function>issue_xlog_fsync</function>. - When <xref linkend="guc-track-io-timing"/> is enabled, the total + When <xref linkend="guc-track-wal-io-timing"/> is enabled, the total amounts of time <function>XLogWrite</function> writes and <function>issue_xlog_fsync</function> syncs WAL data to disk are counted as <varname>write_time</varname> and <varname>fsync_time</varname> in @@ -828,7 +828,7 @@ <literal>fsync</literal>, or <literal>fsync_writethrough</literal>, the write operation moves WAL buffers to kernel cache and <function>issue_xlog_fsync</function> syncs them to disk. Regardless - of the setting of <varname>track_io_timing</varname>, the number + of the setting of <varname>track_wal_io_timing</varname>, the number of times <function>XLogWrite</function> writes and <function>issue_xlog_fsync</function> syncs WAL data to disk are also counted as <varname>writes</varname> and <varname>fsyncs</varname> |