Re: MERGE ... RETURNING

On 2023-Jul-05, Gurjeet Singh wrote:

> +BEGIN;
> +COPY (
> + MERGE INTO sq_target t
> + USING v
> + ON tid = sid
> + WHEN MATCHED AND tid > 2 THEN
> + UPDATE SET balance = t.balance + delta
> + WHEN NOT MATCHED THEN
> + INSERT (balance, tid) VALUES (balance + delta, sid)
> + WHEN MATCHED AND tid < 2 THEN
> + DELETE
> + RETURNING pg_merge_action(), t.*
> +) TO stdout;
> +DELETE 1 100
> +ROLLBACK;
>
> I expected the .out file to have captured the stdout. I'm gradually,
> and gladly, re-learning bits of the test infrastructure.
>
> The DELETE command tag in the output does not feel appropriate for a
> COPY command that's using MERGE as the source of the data.

You misread this one :-) The COPY output is there, the tag is not. So
DELETE is the value from pg_merge_action(), and "1 100" correspond to
the columns in the the sq_target row that was deleted. The command tag
is presumably MERGE 1.

--
Álvaro Herrera Breisgau, Deutschland — https://www.EnterpriseDB.com/