Date: Sat, 12 Oct 2024 12:37:23 -0400
From: Bruce Momjian <bruce@momjian.us>
To: Laurenz Albe <laurenz.albe@cybertec.at>
Cc: Paul A Jungwirth <pj@illuminatedcomputing.com>,
	pgsql-docs@lists.postgresql.org
Subject: Re: Streaming Replication vs Logical
Message-ID: <Zwqlw6RGs4mCnHz9@momjian.us>
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On Sat, Oct 12, 2024 at 07:01:31AM +0200, Laurenz Albe wrote:
> On Fri, 2024-10-11 at 15:53 -0700, Paul A Jungwirth wrote:
> > Our docs seem to contrast "streaming replication" to logical, but
> > these are not really opposites. Sometimes when they say "streaming"
> > they mean "physical".
> > 
> > Probably this is historical: at first physical replication was the
> > only kind of streaming we had.
> > 
> > Personally this has caused me a lot of confusion. For example,
> > recently when I read "Synchronous replication (see Section 26.2.8) is
> > only supported on replication slots used over the streaming
> > replication interface," I took it to mean synchronous replication only
> > worked for physical replication, not logical.
> 
> What you are saying makes a lot of sense, and improving some of this
> is a good thing.
> 
> Our current trminology is a mess.  There are some places in the documentation
> that speak of physical vs. logical replication, while most places use the
> term "streaming replication" for physical replication.  I myself consequently
> speak of "streaming replication" vs. "logical replication", even though both
> stream data.  The protocol section of the documentation describes the
> "streaming replication protocol" and the "logical streaming replication protocol".
> 
> This is confusing, and I am also sometimes confused in the way you described
> above.
> 
> I think the mess is too well established to be really cleaned up.  But adding
> some clarity is a good thing, so +1.

I don't think our current setup is sustainable so I think it does need
to be cleaned up.  Also, physical/logical replication slots also needs
help, I think.

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EDB                                      https://enterprisedb.com

  When a patient asks the doctor, "Am I going to die?", he means 
  "Am I going to die soon?"