Re: max_wal_senders must die

On Tue, Oct 19, 2010 at 12:32 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Robert Haas <robertmhaas(at)gmail(dot)com> writes:
>> On Tue, Oct 19, 2010 at 12:18 PM, Josh Berkus <josh(at)agliodbs(dot)com> wrote:
>>> On 10/19/2010 09:06 AM, Greg Smith wrote:
>>>> 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.
>
>> Setting max_wal_senders to a non-zero value causes additional work to
>> be done every time a transaction commits, aborts, or is prepared.
>
> Yes.  This isn't just a numeric parameter; it's also a boolean
> indicating "do I want to pay the overhead to be prepared to be a
> replication master?".  Josh has completely failed to make a case that
> that should be the default.  In fact, the system would fail to start
> at all if we just changed the default for max_wal_senders and not the
> default for wal_level.
>
>                        regards, tom lane

If the variable is altered such that it is dynamic, could it not be
updated by the postmaster when a connection attempts to begin
replicating?

--
Rob Wultsch
wultsch(at)gmail(dot)com