Bruce Momjian wrote: > Simon Riggs wrote: >> * wal_level = 'hot_standby' doesn't mention that the second parameter >> also needs to be set, nor is there a xref.
Fixed. >> * wal_level doesn't describe what the impacts are on a standby if the >> level is changed on the primary, nor is there a caution or a warning of >> any kind. For example, if a standby is setup with hot_standby = on and >> the primary is set wal_level = archive, does the standby start working >> if the primary changes wal_level = hot_standby? What happens if the >> primary is set wal_level = hot_standby and is then changed to archive? Hmm, feels like it should rather be documented in the hot_standby setting, it affects the standby not the master after all. How about this: --- config.sgml 2 May 2010 11:32:53 -0000 1.274 +++ config.sgml 3 May 2010 09:06:19 -0000 @@ -1931,6 +1933,19 @@ <para> Specifies whether or not you can connect and run queries during recovery, as described in <xref linkend="hot-standby">. + </para> + <para> + Hot Standby requires <xref linkend="guc-wal-level"> to be set + to <literal>hot_standby</> in the primary server. If it was not + while the WAL being replayed was generated, and + <varname>hot_standby</> is set to <literal>on</>, the server will + refuse to start up. Also, if <varname>wal_level</> is changed on + the primary server while a standby is active in hot standby mode, and + the primary server is restarted for the setting to take effect, the + standby will shut down as soon as it sees the checkpoint record + generated at the restart of the primary server. + </para> + <para> The default value is <literal>off</literal>. This parameter can only be set at server start. It only has effect during archive recovery or in standby mode. >> * wal_level doesn't explicitly describe that the levels are in sequence >> and that hot_standby is a superset of archive. It does say: "The default value is <literal>minimal</>, which writes only the information needed to recover from a crash or immediate shutdown. <literal>archive</> adds logging required for WAL archiving, and <literal>hot_standby</> further adds information required to run read-only queries on a standby server." Want to propose a better wording? > I totally agree. Also, there is the new requirement to set wal_level > for PITR, which is not documented as a necessary setup step yet. Fixed. -- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers