Re: Freezing without write I/O

On 10 June 2013 19:58, Heikki Linnakangas <hlinnakangas@vmware.com> wrote:
> On 01.06.2013 23:21, Robert Haas wrote:
>>
>> 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.
>
>
> Here's a first draft. A lot of stuff missing and broken, but "make check"
> passes :-).

Well done, looks like good progress.

--Simon Riggs                   http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services