On Sat, Jan 7, 2012 at 10:55 AM, Simon Riggs <simon@2ndquadrant.com> wrote:
> So there isn't any problem with there being incorrect checksums on
> blocks and you can turn the parameter on and off as often and as
> easily as you want. I think it can be USERSET but I wouldn't want to
> encourage users to see turning it off as a performance tuning feature.
> If the admin turns it on for the server, its on, so its SIGHUP.
>
> Any holes in that I haven't noticed?
And of course, as soon as I wrote that I thought of the problem. We
mustn't make a write that hasn't been covered by a FPW, so we must
know ahead of time whether to WAL log hints or not. We can't simply
turn it on/off any longer, now that we have to WAL log hint bits also.
So thanks for making me think of that.
We *could* make it turn on/off at each checkpoint, but its easier just
to say that it can be turned on/off at server start.
--
Simon Riggs http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
