Re: Why does PostgresNode.pm set such a low value of max_wal_senders?

At Wed, 30 Sep 2020 22:38:59 -0700, Noah Misch <noah(at)leadboat(dot)com> wrote in
noah> Perhaps wal_level=minimal should stop its pedantic call for max_wal_senders=0.
noah> As long as the relevant error messages are clear, it would be fine for
noah> wal_level=minimal to ignore max_wal_senders and size resources as though
noah> max_wal_senders=0. That could be one less snag for end users. (It's not
noah> worth changing solely to save a line in PostgresNode, though.)

At Thu, 01 Oct 2020 09:42:52 -0400, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote in
tgl> On the other point, I think that we should continue to complain
tgl> about max_wal_senders > 0 with wal_level = minimal. If we reduce
tgl> that to a LOG message, which'd be the net effect of trying to be
tgl> laxer, people wouldn't see it and would then wonder why they can't
tgl> start replication.

FWIW, I'm on the noah's side.

One reason of that is that if we implement the in-place setting
relation persistence feature for bulk-data loading, wal_level would
get flipped-then-back between minimal and replica or logical. The
restriction about max_wal_senders is the pain n the ass in that case..

regards.

--
Kyotaro Horiguchi
NTT Open Source Software Center