COPY RETURNING?

Hi.

We are switching a schema type's surrogate/primary key, from `uuid` to
`int`.
That schema has parent-child relationships enforced with foreign-keys.
Our ingestion/schema-loading code uses COPY FROM STDIN BINARY.

Before, the SK/PK was generated client-side, as random uuid.
The ingestion code maintained client-side maps from NKs to uuids,
to be used for FK columns in child-tables COPY'd later.

But now that the SK/PK is an integer identity column generated server-side,
thanks to an implicitly-created sequence, we need that generated per-row
`int` PK.
With a normal prepared statement, we'd use a RETURNING clause, to avoid
a separate round-trip to the server. Can the same somehow be achieved with
COPY?

I'm afraid the answer is no, but I want to ask anyway, maybe there's a way
or work-around?

At the end of the COPY, we do get a ResultSet, so API-wise it was be
possible for it
to contain some rows, I guess, but I'm not sure the COPY protocol supports
returning
rows, nor what the syntax would be to have a COPY RETURNING form of COPY.

Thanks for any insights. --DD