Re: [HACKERS] increasing the default WAL segment size - Mailing list pgsql-hackers

On Tue, Jan 3, 2017 at 6:23 AM, Jim Nasby <Jim.Nasby@bluetreble.com> wrote:
> +               /* Check if wal_segment_size is in the power of 2 */
> +               for (i = 0;; i++, pow2 = pow(2, i))
> +                       if (pow2 >= wal_segment_size)
> +                               break;
> +
> +               if (wal_segment_size != 1 && pow2 > wal_segment_size)
> +               {
> +                       fprintf(stderr, _("%s: WAL segment size must be in the power of 2\n"), progname);
> +                       exit(1);
> +               }

I recall taht pow(x, 2) and x * x result usually in the same assembly
code, but pow() can never be more optimal than a simple
multiplication. So I'd think that it is wiser to avoid it in this code
path. Documentation is missing for the new replication command
SHOW_WAL_SEG. Actually, why not just having an equivalent of the SQL
command and be able to query parameter values?
-- 
Michael