Re: synchronous commit vs. hint bits

On Nov 7, 2011, at 9:35 PM, Robert Haas <robertmhaas@gmail.com> wrote:
> On Mon, Nov 7, 2011 at 6:33 PM, Simon Riggs <simon@2ndquadrant.com> wrote:
>> On Mon, Nov 7, 2011 at 5:26 PM, Simon Riggs <simon@2ndquadrant.com> wrote:
>> 
>>>> 5. Make the WAL writer more responsive, maybe using latches, so that
>>>> it doesn't take as long for the commit record to make it out to disk.
>>> 
>>> I'm working on this already as part of the update for power
>>> reduction/group commit/replication performance.
>> 
>> I extracted this from my current patch for you to test.
> 
> Thank you!
> 
>> Rather useful actually 'cos its allowed me a sensible phasing of the
>> development.
> 
> +1.
> 
> <reads patch>
> 
> Hmm, this is different than what I was expecting, although that's not
> necessarily bad.  What this does is retain wal_writer_delay, but allow
> the WAL writer to be woken up more frequently if there's enough WAL to
> justify it. What I was expecting you to do is eliminate
> wal_writer_delay altogether and drive the wakeups entirely off of the
> latch.

Oh, I think I see why you didn't do that...

Anyway, I'll try to post test results in the morning.

...Robert