Horton

Re: logical decoding and replication of sequences, take 2

Peter Eisentraut <peter.eisentraut@enterprisedb.com>

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From: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
To: Tomas Vondra <tomas.vondra@enterprisedb.com>
Cc: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Masahiko Sawada <sawada.mshk@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>
Date: 2023-05-11T13:54:34Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Migrate logical slots to the new node during an upgrade.

  2. Make test_decoding ddl.out shorter

  3. Fix snapshot handling in logicalmsg_decode

  4. doc: Adjust a few more references to "postmaster"

  5. Revert "Logical decoding of sequences"

On 02.04.23 19:46, Tomas Vondra wrote:
> OK, I took a stab at this, see the attached 0007 patch which bumps the
> protocol version, and allows the subscriber to specify "sequences" when
> starting the replication, similar to what we do for the two-phase stuff.
> 
> The patch essentially adds 'sequences' to the replication start command,
> depending on the server version, but it can be overridden by "sequences"
> subscription option. The patch is pretty small, but I wonder how much
> smarter this should be ...

I think this should actually be much simpler.

All the code needs to do is:

- Raise protocol version (4->5)  (Your patch does that.)

- pgoutput_sequence() checks whether the protocol version is >=5 and if 
not it raises an error.

- Subscriber uses old protocol if the remote end is an older PG version. 
  (Your patch does that.)

I don't see the need for the subscriber to toggle sequences explicitly 
or anything like that.