Re: Proposal for CSN based snapshots

On Wed, Aug 27, 2014 at 10:42 AM, Heikki Linnakangas <
hlinnakangas(at)vmware(dot)com> wrote:

> On 08/27/2014 09:40 AM, Heikki Linnakangas wrote:
>
>> On 08/27/2014 08:23 AM, Jeff Davis wrote:
>>
>>> On Tue, 2014-08-26 at 13:45 +0300, Heikki Linnakangas wrote:
>>>
>>>> Yeah. This patch in the current state is likely much much slower than
>>>> unpatched master, except in extreme cases where you have thousands of
>>>> connections and short transactions so that without the patch, you spend
>>>> most of the time acquiring snapshots.
>>>>
>>>
>>> What else are you looking to accomplish with this patch during this
>>> 'fest? Bug finding? Design review? Performance testing?
>>>
>>
>> Design review, mostly. I know the performance still sucks. Although if
>> you can foresee some performance problems, aside from the extra CSNLOG
>> lookups, it would be good to know.
>>
>
> I think for this commitfest, I've gotten as much review of this patch that
> I can hope for. Marking as "Returned with Feedback". But of course, feel
> free to continue reviewing and commenting ;-).

What is current state of this patch? Does community want CSN based
snapshots?
Last email in lists was in August 2014. Huawei did talk about their further
research on this idea at PGCon and promised to publish their patch in open
source.
http://www.pgcon.org/2015/schedule/events/810.en.html
However, it isn't published yet, and we don't know how long we could wait
for it.
Now, our company have resources to work on CSN based snapshots for 9.6. If
Huawei will not publish their patch, we can pick up this work from last
community version of this patch.

------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company