Re: sorry, too many standbys already vs. MaxWalSenders vs. max_wal_senders

Robert Haas wrote:
> After snapshotting my master using hot backup to create a workable
> slave instance, I created recovery.conf on the slave and tried to get
> it to connect to the master and stream WAL.
> 
> This led to the message "sorry, too many standbys already", which did
> not immediately clue me in as to what I needed to do to fix the
> problem.  Grepping the source code for the error message revealed that
> the problem was that MaxWalSenders was zero.  A few seconds further
> head-scratching revealed that this was the GUC max_wal_senders, which
> I duly increased from 0 to 1, after which it worked.
> 
> I think perhaps this error message needs some adjustment.  It should
> be reasonably possible to guess the name of the GUC that needs
> increasing based on the error message, and it currently isn't.  Also
> I'd vote for making the variable name max_wal_senders rather than
> MaxWalSenders, but maybe that's being persnicketty.

Glad the error message has been improved.  I was bitten by this exact
error message and didn't know the cause for a while, and was going to
suggest such a fix.

--  Bruce Momjian  <bruce@momjian.us>        http://momjian.us EnterpriseDB
http://enterprisedb.com