Re: max_standby_delay considered harmful

Bruce Momjian wrote:
> Remember, delaying wal application just delays making the standby a
> master and makes the slave data appear staler.  We can just tell people
> that the larger their queries are, the larger this delay will be.  If
> they want to control this, they can set 'statement_timeout' already.
>   

While a useful defensive component, statement_timeout is a user setting, 
so it can't provide guaranteed protection against a WAL application 
denial of service from a long running query.  A user that overrides the 
system setting and kicks off a long query puts you right back into 
needing a timeout to ensure forward progress of standby replay.

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