On Fri, Nov 21, 2014 at 12:55 PM, Josh Berkus <j...@agliodbs.com> wrote: > On 11/21/2014 09:35 AM, Alex Shulgin wrote: >> Hello, >> >> Here's an attempt to revive this patch. > > Yayy! Thank you. > >>> People might not like me for the suggestion, but I think we should >>> simply always include a 'recovery.conf' in $PGDATA >>> unconditionally. That'd make this easier. >>> Alternatively we could pass a filename to --write-recovery-conf. >> >> Well, the latest version of this patch fails to start when it sees >> 'recovery.conf' in PGDATA: >> >> FATAL: "recovery.conf" is not supported anymore as a recovery method >> DETAIL: Refer to appropriate documentation about migration methods >> >> I've missed all the discussion behind this decision and after reading >> the ALTER SYSTEM/conf.d thread I'm even more confused so I'd like >> someone more knowledgeable to speak up on the status of this. > > The argument was that people wanted to be able to have an empty > recovery.conf file as a "we're in standby" trigger so that they could > preserve backwards compatibility with external tools. I don't agree > with this argument, but several people championed it. >
well, my approach was that postgres just ignore the file completely. I mean, recovery.conf will no longer mean anything special. Then, every tool that create recovery.conf in $PGDATA only has to add an ALTER SYSTEM to include it >> The docs use the term "continuous recovery". >> >> Either way, from the code it is clear that we only stay in recovery if >> standby_mode is directly turned on. This makes the whole check for a >> specially named file unnecessary, IMO: we should just check the value of >> standby_mode (which is off by default). > no. currently we enter in recovery mode when postgres see a recovery.conf and stays in recovery mode when standby_mode is on or an appropiate restore_command is provided. which means recovery.conf has two uses: 1) start in recovery mode (not continuous) 2) provide parameters for recovery mode and for streaming we still need a "recovery trigger" file that forces postgres to start in recovery mode and acts accordingly to recovery GUCs > So, what happens when someone does "pg_ctl promote"? Somehow > standby_mode needs to get set to "off". Maybe we write "standby_mode = > off" to postgresql.auto.conf? > we need to delete or rename the "recovery trigger" file, all standby GUCs are ignored (and recovery GUCs should be ignored too) unless you're in recovery mode >> By the way, is there any use in setting standby_mode=on and any of the >> recovery_target* GUCs at the same time? > > See my thread on this topic from last week. Short answer: No. > haven't read that thread, will do > >>>> /* File path names (all relative to $PGDATA) */ >>>> -#define RECOVERY_COMMAND_FILE "recovery.conf" >>>> -#define RECOVERY_COMMAND_DONE "recovery.done" >>>> +#define RECOVERY_ENABLE_FILE "standby.enabled" >>> >>> Imo the file and variable names should stay coherent. >> >> Yes, once we settle on the name (and if we really need that extra >> trigger file.) > yes, we need it. but other names were suggested "standby.enabled" transmit the wrong idea > Personally, if we have three methods of promotion: > > 1) pg_ctl promote > 2) edit postgresql.conf and reload > 3) ALTER SYSTEM SET and reload > > ... I don't honestly think we need a 4th method for promotion. > this is not for promotion, this is to force postgres to start in recovery mode and read recovery configuration parameters. > The main reason to want a "we're in recovery file" is for PITR rather > than for replication, where it has a number of advantages as a method, > the main one being that recovery.conf is unlikely to be overwritten by > the contents of the backup. > only that you need to start in recovery mode to start replication -- Jaime Casanova www.2ndQuadrant.com Professional PostgreSQL: Soporte 24x7 y capacitación Phone: +593 4 5107566 Cell: +593 987171157 -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
