Re: Do we need pre-allocate WAL files during end-of-recovery checkpoint?

If the segment size is 16MB it shouldn't take much time but higher segment
values this can be a problem. But again, the current segment has to be
filled 75% to precreate new one. I am not sure how much we gain. Do you
have some numbers with different segment sizes?

On Mon, Dec 6, 2021 at 4:51 AM Bharath Rupireddy <
bharath(dot)rupireddyforpostgres(at)gmail(dot)com> wrote:

> Hi,
>
> The function PreallocXlogFiles doesn't get called during
> end-of-recovery checkpoint in CreateCheckPoint, see [1]. The server
> becomes operational after the end-of-recovery checkpoint and may need
> WAL files. However, I'm not sure how beneficial it is going to be if
> the WAL is pre-allocated (as PreallocXlogFiles just allocates only 1
> extra WAL file).
>
> Thoughts?
>
> [1]
> /*
> * An end-of-recovery checkpoint is really a shutdown checkpoint, just
> * issued at a different time.
> */
> if (flags & (CHECKPOINT_IS_SHUTDOWN | CHECKPOINT_END_OF_RECOVERY))
> shutdown = true;
> else
> shutdown = false;
>
> /*
> * Make more log segments if needed. (Do this after recycling old log
> * segments, since that may supply some of the needed files.)
> */
> if (!shutdown)
> PreallocXlogFiles(recptr, checkPoint.ThisTimeLineID);
>
> Regards,
> Bharath Rupireddy.
>
>
>