Re: Removing support for FE/BE protocol version 2

> PostgreSQL 14, which was released in 2021, removed protocol version 2
> support. The last version supporting protocol version 2 was 13, which
> was EOLed in November 2025. So, existing supported PostgreSQL versions
> do not accept the protocol version 2 anymore (more precisely, they
> response with "unsupported protocol version" error when the protocol
> is requested).
>
> I would like to propose removing support for FE/BE protocol version 2
> in upcoming v4.8. If the version 2 startup message arrives, pgpool
> responds with "unsupported protocol version" error, which is the same
> behavior as PostgreSQL server.
>
> The merits of dropping v2 protocol are:
>
> - Simplifying our code base. There are pretty large number of code
> path which handles v2 protocol.
>
> - Removing untested codes. Our regression tests do not include v2
> protocol cases.
>
> We cannot support the version 2 protocol forever. Dropping it is only
> a matter of time. As I already mentioned above, all supported
> PostgreSQL versions finally drop the v2 protocol, I think v4.8 is the
> good timing to remove v2 protocol for us.
>
> Thoughts?

3 months ago I posted this message and haven't seen any
replies. Assuming no objection, I have started to work on
this. Attached are the in progress patch sets.

001 is to reject the v2 protocol startup packet. If v2 frontend
connects, raise a FATAL error.

002 is to remove v2 protocol processing in process reporting modules
(e.g. show pool_nodes).

I plan to work on rest of source files that handle the v2 protocol.

src/auth/pool_auth.c
src/auth/pool_hba.c
src/context/pool_query_context.c
src/protocol/pool_process_query.c
src/protocol/pool_proto_modules.c
src/query_cache/pool_memqcache.c
src/streaming_replication/pool_worker_child.c
src/test/regression/tests/010.rewrite_timestamp/timestamp/main.c
src/utils/error/elog.c

I hope I am not missing anything...

Regards,
--
Tatsuo Ishii
SRA OSS K.K.
English: http://www.sraoss.co.jp/index_en/
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