Simon Riggs <simon@2ndquadrant.com> writes:
> On Wed, 2007-11-21 at 18:16 +0100, Zeugswetter Andreas ADI SD wrote:
>> Maybe it is time for making WAL segment size
>> changeable in the conf with a clean shutdown.
> I think its too late in the release cycle to fully consider all the
> implications of that. 16MB is hardcoded in lots of places.
Starting with the WAL file names. You couldn't even find the last
checkpoint record if this were changed between shutdown and restart;
you'd very likely go looking under the wrong filename, and even if
you hit on an existent filename you'd be looking at the wrong offset
within it.
I don't think that should even be a TODO item --- it seems far more
likely to provide a foot-gun than useful capability.
Whether 16MB is still a reasonable default segment size is worth
questioning, though I don't think that increasing it is an open-and-shut
proposition. Larger segments mean more overhead in configurations that
force frequent segment switches, for instance.
regards, tom lane