Re: New WAL record to detect the checkpoint redo location - Mailing list pgsql-hackers

On Thu, Aug 17, 2023 at 10:52 AM Michael Paquier <michael@paquier.xyz> wrote:
>
> On Tue, Aug 15, 2023 at 02:23:43PM +0530, Dilip Kumar wrote:
> > Yeah, good idea, actually we can do this insert outside of the
> > exclusive insert lock and set the LSN of this insert as the
> > checkpoint. redo location.  So now we do not need to compute the
> > checkpoint. redo based on the current insertion point we can directly
> > use the LSN of this record.  I have modified this and I have also
> > moved some other code that is not required to be inside the WAL
> > insertion lock.
>
> Looking at this patch, I am bit surprised to see that the redo point
> maps with the end location of the CHECKPOINT_REDO record as it is the
> LSN returned by XLogInsert(), not its start LSN.

Yeah right, actually I was confused, I assumed it will return the
start LSN of the record.  And I do not see any easy way to identify
the Start LSN of this record so maybe this solution will not work.  I
will have to think of something else.  Thanks for pointing it out.

--
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com