This is a summary of proposed changes to the recovery.conf API for v10. These are based in part on earlier discussions, and represent a minimal modification to current usage.
Proposed changes (with reference to patches from Abhijit Menon-Sen and myself) * pg_ctl start -M (normal|recover|continue) pg_ctl can now start the server directly as a standby, similar to the way pg_ctl promote works. The internal implementation is also similar, with pg_ctl writing a "recovery.trigger" file that initiates recovery in the same way recovery.conf used to do. It is still possible to manually add a file called "recovery.trigger" and have that work if users desire that mechanism. Different startup methods can be selected with the <option>-M</option> option. <quote>Normal</quote> mode starts the server for read/write, overriding any previous use in Recover mode. <quote>Recover</quote> mode starts the server as a standby server which expects to receive changes from a primary/master server using physical streaming replication or is used for performing a recovery from backup. <quote>Continue</quote> mode is the default and will startup the server in whatever mode it was in at last proper shutdown, or as modified by any trigger files present. (Patch: recovery_startup_r10_api.v1b.patch) * $DATADIR/recovery.conf no longer triggers recovery (Patch: recovery_startup_r10_api.v1b.patch) * Recovery parameters would now be part of the main postgresql.conf infrastructure Any parameters set in $DATADIR/recovery.conf will be read after the main parameter file, similar to the way that postgresql.conf.auto is read. (Abhijit) * pg_basebackup -R will continue to generate a parameter file called recovery.conf as it does now, but will also create a file named recovery.trigger. (This part is WIP; patch doesn't include implementation for tar format yet) * Parameters All of the parameters formerly set in recovery.conf can be set in postgresql.conf using RELOAD These parameters will have no defaults in postgresql.conf.sample Setting them has no effect during normal running, or once recovery ends. https://www.postgresql.org/docs/devel/static/archive-recovery-settings.html https://www.postgresql.org/docs/devel/static/recovery-target-settings.html https://www.postgresql.org/docs/devel/static/standby-settings.html (Abhijit) Related cleanup * Promotion signal file is now called "promote.trigger" rather than just "promote" * Remove user configurable "trigger_file" mechanism - use "promote.trigger" for all cases * Remove Fallback promote mechanism, so all promotion is now "fast" in xlog.c * Rename CheckForStandbyTrigger() to CheckForPromoteTrigger() for clarity (Patch: recovery_startup_r10_api.v1b.patch) -- Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
recovery_startup_r10_api.v1b.patch
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