Re: Freeze avoidance of very large table.

On Thu, May 28, 2015 at 11:34 AM, Sawada Masahiko <sawada(dot)mshk(at)gmail(dot)com> wrote:
> On Thu, Apr 30, 2015 at 8:07 PM, Sawada Masahiko <sawada(dot)mshk(at)gmail(dot)com> wrote:
>> On Fri, Apr 24, 2015 at 11:21 AM, Sawada Masahiko <sawada(dot)mshk(at)gmail(dot)com> wrote:
>>> On Fri, Apr 24, 2015 at 1:31 AM, Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com> wrote:
>>>> On 4/23/15 11:06 AM, Petr Jelinek wrote:
>>>>>
>>>>> On 23/04/15 17:45, Bruce Momjian wrote:
>>>>>>
>>>>>> On Thu, Apr 23, 2015 at 09:45:38AM -0400, Robert Haas wrote:
>>>>>> Agreed, no extra file, and the same write volume as currently. It would
>>>>>> also match pg_clog, which uses two bits per transaction --- maybe we can
>>>>>> reuse some of that code.
>>>>>>
>>>>>
>>>>> Yeah, this approach seems promising. We probably can't reuse code from
>>>>> clog because the usage pattern is different (key for clog is xid, while
>>>>> for visibility/freeze map ctid is used). But visibility map storage
>>>>> layer is pretty simple so it should be easy to extend it for this use.
>>>>
>>>>
>>>> Actually, there may be some bit manipulation functions we could reuse;
>>>> things like efficiently counting how many things in a byte are set. Probably
>>>> doesn't make sense to fully refactor it, but at least CLOG is a good source
>>>> for cut/paste/whack.
>>>>
>>>
>>> I agree with adding a bit that indicates corresponding page is
>>> all-frozen into VM, just like CLOG.
>>> I'll change the patch as second version patch.
>>>
>>
>> The second patch is attached.
>>
>> In second patch, I added a bit that indicates all tuples in page are
>> completely frozen into visibility map.
>> The visibility map became a bitmap with two bit per heap page:
>> all-visible and all-frozen.
>> The logics around vacuum, insert/update/delete heap are almost same as
>> previous version.
>>
>> This patch lack some point: documentation, comment in source code,
>> etc, so it's WIP patch yet,
>> but I think that it's enough to discuss about this.
>>
>
> The previous patch is no longer applied cleanly to HEAD.
> The attached v2 patch is latest version.
>
> Please review it.

Attached new rebased version patch.
Please give me comments!

Regards,

--
Sawada Masahiko