Re: pg_sequence catalog

On Sun, Sep 11, 2016 at 2:15 PM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> On Sun, Sep 11, 2016 at 12:39 AM, Andres Freund <andres(at)anarazel(dot)de> wrote:
>> On 2016-09-10 17:23:21 +0530, Amit Kapila wrote:
>>> >
>>>
>>> I may be missing something here, but why would it contend on a lock,
>>> as per locking scheme proposed by Alvaro, access to sequence object
>>> will need a share lock on buffer page.
>>
>> To make checkpointing/bgwriter work correctly we need exclusive locks on
>> pages while writing..., or some new lock level preventing the page from
>> being written out, while "shared dirtying" locks are being held.
>>
>
> Right and I think you have a very valid concern, but if we think that
> storing multiple sequences on a same page is a reasonable approach,
> then we can invent some locking mechanism as indicated by you such
> that two writes on same page won't block each other, but they will be
> blocked with bgwriter/checkpointer.

This thread has died a couple of weeks back, so I am marking it as
returned with feedback by seeing the discussion that has been done.
Feel free to update the patch if you think that's not adapted.
--
Michael