Re: doc: add note that wal_level=logical doesn't set up logical replication in itself

From: "David G(dot) Johnston" <david(dot)g(dot)johnston(at)gmail(dot)com>
To: Euler Taveira <euler(at)eulerto(dot)com>
Cc: Florents Tselai <florents(dot)tselai(at)gmail(dot)com>, Chao Li <li(dot)evan(dot)chao(at)gmail(dot)com>, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: doc: add note that wal_level=logical doesn't set up logical replication in itself
Date: 2026-03-04 16:00:37
Message-ID: CAKFQuwaUyN8LeFXmwD2ZiR3M3GZ66kELsTU3JBvGuyS0Ombvww@mail.gmail.com
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On Wed, Mar 4, 2026 at 7:11 AM Euler Taveira <euler(at)eulerto(dot)com> wrote:

> >
> > Something like:
> > Note that setting this parameter only enables the required WAL format;
> > it does not configure logical replication by itself.
> >
>
> I don't think such note should be added. If the DBA doesn't know how to
> setup
> logical replication, it should read the Logical Replication chapter.
>
>
Yeah, I don't think this change is directly warranted. But in trying to
figure out what we can do to improve matters I find that the documentation
here has some room to improve that may indeed reduce confusion and be more
informative than the proposed single line addition. In particular, now
that we have effective_wal_level it is unclear why people would even be
here changing wal_level in the first place. The quick start guide to
logical replication is at least partially at fault in that regard.

Since the suggestion made here don't directly apply to the subject of this
email thread, and I've some other suggestions as well, I've started a new
thread here:

https://www.postgresql.org/message-id/CAKFQuwY=WLF0OH8JE5T8S=aj0LBydiSn02fkRE73Sm_KSLRqJQ@mail.gmail.com

David J.

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