On 27 May 2014 07:42, Greg Stark <stark@mit.edu> wrote:
> On Tue, May 27, 2014 at 10:07 AM, Heikki Linnakangas
> <hlinnakangas@vmware.com> wrote:
>>
>> On 05/26/2014 02:26 PM, Greg Stark wrote:
>>>
>>>> Another idea would be to have separate checkpoints for each buffer
>>> partition. You would have to start recovery from the oldest checkpoint of
>>> any of the partitions.
>>
>> Yeah. Simon suggested that when we talked about this, but I didn't understand how that works at the time. I think I
donow. The key to making it work is distinguishing, when starting recovery from the latest checkpoint, whether a record
fora given page can be replayed safely. I used flags on WAL records in my proposal to achieve this, but using buffer
partitionsis simpler.
>
> Interesting. I just thought of it independently.
Actually, I heard it from Doug Tolbert in 2005, based on how another
DBMS coped with that issue.
-- Simon Riggs http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services