Re: [Proposal] Fully WAL logged CREATE DATABASE - No Checkpoints

On Mon, Dec 6, 2021 at 7:53 PM Ashutosh Sharma <ashu(dot)coek88(at)gmail(dot)com> wrote:
>
> Thank you, Dilip for the quick response. I am okay with the changes done in the v7 patch.
>
> One last point - If we try to clone a huge database, as expected CREATE DATABASE emits a lot of WALs, causing a lot of intermediate checkpoints which seems to be affecting the performance slightly.

Yeah, that is a valid point because instead of just one WAL for
createdb we will generate WAL for each page in the database, so I
agree that if the max_wal_size is not enough for those WALs then we
might have to pay the cost of multiple checkpoints. However, if we
compare it with the current mechanism then now it is a forced
checkpoint and there is no way to avoid it whereas with the new
approach user can set enough max_wal_size and they can avoid it. So
in other words now the checkpoint is driven by the amount of resource
which is true for any other operation e.g. ALTER TABLE SET TABLESPACE
so now it is in more sync with the rest of the system, but without the
patch, it was a special purpose forced checkpoint only for the
createdb.

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