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| author | Heikki Linnakangas <heikki.linnakangas@iki.fi> | 2013-12-13 16:26:14 +0200 |
|---|---|---|
| committer | Heikki Linnakangas <heikki.linnakangas@iki.fi> | 2013-12-13 16:26:14 +0200 |
| commit | 50e547096c4858a68abf09894667a542cc418315 (patch) | |
| tree | 4d1005e1b0d33cd43eb9ff872f5f92275938b20c /doc/src | |
| parent | 56afe8509ec3057e06ebe244e51272511f05decb (diff) | |
| download | postgresql-50e547096c4858a68abf09894667a542cc418315.tar.gz postgresql-50e547096c4858a68abf09894667a542cc418315.zip | |
Add GUC to enable WAL-logging of hint bits, even with checksums disabled.
WAL records of hint bit updates is useful to tools that want to examine
which pages have been modified. In particular, this is required to make
the pg_rewind tool safe (without checksums).
This can also be used to test how much extra WAL-logging would occur if
you enabled checksums, without actually enabling them (which you can't
currently do without re-initdb'ing).
Sawada Masahiko, docs by Samrat Revagade. Reviewed by Dilip Kumar, with
further changes by me.
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/config.sgml | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/doc/src/sgml/config.sgml b/doc/src/sgml/config.sgml index 8896988e5aa..f0794467ba4 100644 --- a/doc/src/sgml/config.sgml +++ b/doc/src/sgml/config.sgml @@ -1944,6 +1944,32 @@ include 'filename' </listitem> </varlistentry> + <varlistentry id="guc-wal-log-hintbits" xreflabel="wal_log_hintbits"> + <term><varname>wal_log_hintbits</varname> (<type>boolean</type>)</term> + <indexterm> + <primary><varname>wal_log_hintbits</> configuration parameter</primary> + </indexterm> + <listitem> + <para> + When this parameter is <literal>on</>, the <productname>PostgreSQL</> + server writes the entire content of each disk page to WAL during the + first modification of that page after a checkpoint, even for + non-critical modifications of so-called hint bits. + </para> + + <para> + If data checksums are enabled, hint bit updates are always WAL-logged + and this setting is ignored. You can use this setting to test how much + extra WAL-logging would occur if your database had data checksums + enabled. + </para> + + <para> + This parameter can only be set at server start. The default value is <literal>off</>. + </para> + </listitem> + </varlistentry> + <varlistentry id="guc-wal-buffers" xreflabel="wal_buffers"> <term><varname>wal_buffers</varname> (<type>integer</type>)</term> <indexterm> |