On Wed, Feb 19, 2025 at 11:15 PM Robert Treat <[email protected]> wrote: > On Wed, Feb 19, 2025 at 10:07 PM Bruce Momjian <[email protected]> wrote: >> 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. >> > > The attached patch expands on Paul's original patch, further consolidating > around the terms "streaming physical replication" and "streaming logical > replication" in places where it makes sense. I would note that there are > places where "streaming replication" makes sense (when it applies to both > types) and potentially when "physical replication" might make sense when we > could be talking about either streaming or wal shipping, so I don't think we > can completely eliminate that, but hopefully this improves what we have. > >> >> 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. >> > > I took a look through some of the replication slot stuff and ISTM that it > basically gets the streaming logical/physical replication distinctions > correct, and I *think* > it gets the slot distinctions correct as well, but to the degree there might > be some issue there, I think it could be addressed separately. >
Hey Bruce, Your recent commit on this topic [1] reminded me of the patch from earlier this year meant to address some other areas where we are blurry about using streaming vs physical vs logical replication. I think (I might possibly still be jet lagged) I have updated the previous version of that patch against HEAD, attached, and bumping it up for review. [1] https://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=a5b69e30731fb623715ecf4c8073c0f2dee41678;hp=acbc9beaaed6ee88416e1dcef5df77fd5baba0be) Robert Treat https://xzilla.net
v3-0001-Clarify-usage-of-the-term-streaming-replication.patch
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