diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/config.sgml | 33 |
1 files changed, 17 insertions, 16 deletions
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index adab2f8378d..dcd06634fe6 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -1903,10 +1903,10 @@ include_dir 'conf.d' <xref linkend="guc-shared-buffers">, but smaller than the OS's page cache, where performance might degrade. This setting may have no effect on some platforms. The valid range is between - <literal>0</literal>, which disables controlled writeback, and + <literal>0</literal>, which disables forced writeback, and <literal>2MB</literal>. The default is <literal>512kB</> on Linux, - <literal>0</> elsewhere. (Non-default values of - <symbol>BLCKSZ</symbol> change the default and maximum.) + <literal>0</> elsewhere. (If <symbol>BLCKSZ</symbol> is not 8kB, + the default and maximum values scale proportionally to it.) This parameter can only be set in the <filename>postgresql.conf</> file or on the server command line. </para> @@ -2055,10 +2055,10 @@ include_dir 'conf.d' that are bigger than <xref linkend="guc-shared-buffers">, but smaller than the OS's page cache, where performance might degrade. This setting may have no effect on some platforms. The valid range is - between <literal>0</literal>, which disables controlled writeback, - and <literal>2MB</literal>. The default is <literal>0</> (i.e. no - flush control). (Non-default values of <symbol>BLCKSZ</symbol> - change the maximum.) + between <literal>0</literal>, which disables forced writeback, + and <literal>2MB</literal>. The default is <literal>0</>, i.e., no + forced writeback. (If <symbol>BLCKSZ</symbol> is not 8kB, + the maximum value scales proportionally to it.) </para> </listitem> </varlistentry> @@ -2518,10 +2518,11 @@ include_dir 'conf.d' <para> Specifies how often the WAL writer flushes WAL. After flushing WAL it sleeps for <varname>wal_writer_delay</> milliseconds, unless woken up - by an asynchronously committing transaction. In case the last flush + by an asynchronously committing transaction. If the last flush happened less than <varname>wal_writer_delay</> milliseconds ago and less than <varname>wal_writer_flush_after</> bytes of WAL have been - produced since, WAL is only written to the OS, not flushed to disk. + produced since, then WAL is only written to the operating system, not + flushed to disk. The default value is 200 milliseconds (<literal>200ms</>). Note that on many systems, the effective resolution of sleep delays is 10 milliseconds; setting <varname>wal_writer_delay</> to a value that is @@ -2540,12 +2541,12 @@ include_dir 'conf.d' </term> <listitem> <para> - Specifies how often the WAL writer flushes WAL. In case the last flush + Specifies how often the WAL writer flushes WAL. If the last flush happened less than <varname>wal_writer_delay</> milliseconds ago and less than <varname>wal_writer_flush_after</> bytes of WAL have been - produced since, WAL is only written to the OS, not flushed to disk. - If <varname>wal_writer_flush_after</> is set to <literal>0</> WAL is - flushed every time the WAL writer has written WAL. The default is + produced since, then WAL is only written to the operating system, not + flushed to disk. If <varname>wal_writer_flush_after</> is set + to <literal>0</> then WAL data is flushed immediately. The default is <literal>1MB</literal>. This parameter can only be set in the <filename>postgresql.conf</> file or on the server command line. </para> @@ -2665,10 +2666,10 @@ include_dir 'conf.d' that are bigger than <xref linkend="guc-shared-buffers">, but smaller than the OS's page cache, where performance might degrade. This setting may have no effect on some platforms. The valid range is - between <literal>0</literal>, which disables controlled writeback, + between <literal>0</literal>, which disables forced writeback, and <literal>2MB</literal>. The default is <literal>256kB</> on - Linux, <literal>0</> elsewhere. (Non-default values of - <symbol>BLCKSZ</symbol> change the default and maximum.) + Linux, <literal>0</> elsewhere. (If <symbol>BLCKSZ</symbol> is not + 8kB, the default and maximum values scale proportionally to it.) This parameter can only be set in the <filename>postgresql.conf</> file or on the server command line. </para> |