From: | Beena Emerson <memissemerson(at)gmail(dot)com> |
---|---|
To: | Michael Paquier <michael(dot)paquier(at)gmail(dot)com> |
Cc: | PostgreSQL mailing lists <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: increasing the default WAL segment size |
Date: | 2017-01-05 11:39:05 |
Message-ID: | CAOG9ApF8RqeuH=Pvif6CqntYc3AZxnbLXzqVbGWBh9TJP=tWqQ@mail.gmail.com |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-hackers |
Hello,
On Tue, Jan 3, 2017 at 5:46 PM, Michael Paquier <michael(dot)paquier(at)gmail(dot)com>
wrote:
> On Tue, Jan 3, 2017 at 6:23 AM, Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)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.
As mentioned earlier, documents are not fully updated.
> Actually, why not just having an equivalent of the SQL
> command and be able to query parameter values?
>
This patch only needed the wal_segment_size and hence I made this specific
command.
How often and why would we need other parameter values in the replication
connection?
Making it a more general command to fetch any parameter can be a separate
topic. If it gets consensus, maybe it could be done and used here.
Thank you,
Beena Emerson
Have a Great Day!
From | Date | Subject | |
---|---|---|---|
Next Message | Etsuro Fujita | 2017-01-05 11:44:51 | Re: Push down more full joins in postgres_fdw |
Previous Message | Beena Emerson | 2017-01-05 11:38:54 | Re: increasing the default WAL segment size |