On Fri, Jan 6, 2012 at 9:44 PM, Robert Haas <robertmhaas@gmail.com> wrote:
>> Writing pages during recovery doesn't need WAL. If we crash, we replay
>> using the already generated WAL.
>
> Which is all fine, except when you start making changes that are not
> WAL-logged. Then, you have the same torn page problem that exists
> when you it in normal running.
Yes, of course. My point is that this is not a blocker to using
checksums, only that some actions cannot occur on the standby but the
replay of changes is not in danger.
page_checksums is an optional parameter, so you can turn it on or off
on the standby as you wish. People frequently have a standby dedicated
to HA and other standbys for queries. So this is all normal and
natural.
page_checksums will default to 'off' in the final patch anyway, in my
understanding.
--
Simon Riggs http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
