Re: Immediate shutdown and system(3)

Greg Stark wrote:
> This isn't the first time we've run into the problem that we've run
> out of signals. I think we need to multiplex all our event signals
> onto a single signal and use some other mechanism to indicate the type
> of message.

Yeah. A patch to do that was discussed a while ago, as Fujii's 
synchronous replication patch bumped into that as well. I don't feel 
like changing the signaling so dramatically right now, however.

> Do we really need a "promote to master" message at all? Is pg_standby
> responsible for this or could the master write out the configuration
> changes necessary itself?

The way pg_standby works is that it keeps waiting for new WAL files to 
arrive, until it's told to stop and return a non-zero exit code. 
Non-zero exit code from restore_command basically means "file not 
found", making the startup process to end recovery and start up the 
database. There's two ways to tell pg_standby to stop: create a trigger 
file with a particular name, or signal it with SIGINT or SIGQUIT.

--   Heikki Linnakangas  EnterpriseDB   http://www.enterprisedb.com