On Sat, Jun 1, 2013 at 2:48 PM, Heikki Linnakangas
<hlinnakangas@vmware.com> wrote:
>> We define a new page-level bit, something like PD_RECENTLY_FROZEN.
>> When this bit is set, it means there are no unfrozen tuples on the
>> page with XIDs that predate the current half-epoch. Whenever we know
>> this to be true, we set the bit. If the page LSN crosses more than
>> one half-epoch boundary at a time, we freeze the page and set the bit.
>> If the page LSN crosses exactly one half-epoch boundary, then (1) if
>> the bit is set, we clear it and (2) if the bit is not set, we freeze
>> the page and set the bit.
>
> Yep, I think that would work. Want to write the patch, or should I? ;-)
Have at it. I think the tricky part is going to be figuring out the
synchronization around half-epoch boundaries.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
