Re: Remove useless pointer advance in StatsShmemInit() - Mailing list pgsql-hackers

On Mon, Aug 18, 2025 at 09:04:59AM +0000, Bertrand Drouvot wrote:
> As StatsShmemInit() is existing code, let's fix it: the pointer is not used after
> its last advance, so that advance is unnecessary and can be removed.
> @@ -180,7 +180,6 @@ StatsShmemInit(void)

          * provides a small efficiency win.
          */
         ctl->raw_dsa_area = p;
-        p += MAXALIGN(pgstat_dsa_init_size());
         dsa = dsa_create_in_place(ctl->raw_dsa_area,
                                   pgstat_dsa_init_size(),
                                   LWTRANCHE_PGSTATS_DSA, NULL);

I'd bet that this is a vestige of the earlier versions discussed for
the pgstats shmem patch, where !IsUnderPostmaster was doing a few more
things with this pointer going down.

One could argue that "p" could be removed, moving the
sizeof(PgStat_ShmemControl) when we set raw_dsa_area, but that's a bit
cleaner with the extra pointer assignment and the comment for
pgStatLocal.shmem.  So, why not.
--
Michael