On Tue, Jun 23, 2026, at 7:39 AM, Amit Kapila wrote:
>
> If we go by the definition of Client/Server from the docs at
> doc/src/sgml/reference.sgml:
> - Client: "The common feature of these applications is that they can
> be run on any host, independent of where the database server resides."
> - Server: "These commands can only be run usefully on the host where
> the database server resides."
>
> So the documented discriminator is locality of the data directory, not
> libpq. By that rule pg_createsubscriber is a server application as
> it takes -D pgdata of the target, and requires that target (a physical
> standby) to run recovery on it. BTW, pg_rewind also takes a remote
> --source-server libpq connection to a live server, yet it's a server
> app, because it rewrites a local data directory. So I think "makes a
> libpq connection" is not the right discriminator; if it were,
> pg_rewind would have to move too.
>
That's my interpretation too. BTW we had this discussion during development [1].
[1] https://www.postgresql.org/message-id/aabc91d2-505b-4412-af08-7dae2df1d437%40app.fastmail.com
--
Euler Taveira
EDB https://www.enterprisedb.com/
