Re: max_wal_senders must die

Josh Berkus wrote:
> Under what bizarre set of circumstances would anyone have runaway 
> connections from replicas to the master?

Cloud computing deployments where additional replicas are brought up 
automatically in response to demand.  It's easy to imagine a situation 
where a standby instance is spawned, starts to sync, and that additional 
load triggers *another* standby to come on board; repeat until the 
master is doing nothing but servicing standby sync requests.  
max_wal_senders provides a safety value for that.

I think Magnus's idea to bump the default to 5 triages the worst of the 
annoyance here, without dropping the feature (which has uses) or waiting 
for new development to complete.  I'd be in favor of just committing 
that change right now, before it gets forgotten about, and then if 
nobody else gets around to further work at least something improved here 
for 9.1.

-- 
Greg Smith, 2ndQuadrant US greg@2ndQuadrant.com Baltimore, MD
PostgreSQL Training, Services and Support  www.2ndQuadrant.us