Re: +(pg_lsn, int8) and -(pg_lsn, int8) operators

On Thu, Apr 23, 2020 at 2:51 PM Fujii Masao <masao(dot)fujii(at)oss(dot)nttdata(dot)com> wrote:
>
> Hi,
>
> I'd like to propose to introduce the +(pg_lsn, int8) and -(pg_lsn, int8)
> operators. The + operator allows us to add the number of bytes into pg_lsn,
> resulting new pg_lsn. The - operator allows us to substract the number
> of bytes from pg_lsn, resulting new pg_lsn. Thought?
> I sometimes need these features for debuging purpose.

As it's presented in the patch I don't see much value in calling it as
LSN arithmetic. If we could do something like LSN of Nth WAL record
+/- <number of WAL records, n> = LSN of N+/- n th log record that
would be interesting. :)

--
Best Wishes,
Ashutosh Bapat