Re: MERGE ... RETURNING

Jeff Davis:
> To summarize, most of the problem has been in retrieving the action
> (INSERT/UPDATE/DELETE) taken or the WHEN-clause number applied to a
> particular matched row. The reason this is important is because the row
> returned is the old row for a DELETE action, and the new row for an
> INSERT or UPDATE action. Without a way to distinguish the particular
> action, the RETURNING clause returns a mixture of old and new rows,
> which would be hard to use sensibly.

It seems to me that all of this is only a problem, because there is only
one RETURNING clause.

Dean Rasheed wrote in the very first post to this thread:
> I considered allowing a separate RETURNING list at the end of each
> action, but rapidly dismissed that idea. Firstly, it introduces
> shift/reduce conflicts to the grammar. These can be resolved by making
> the "AS" before column aliases non-optional, but that's pretty ugly,
> and there may be a better way. More serious drawbacks are that this
> syntax is much more cumbersome for the end user, having to repeat the
> RETURNING clause several times, and the implementation is likely to be
> pretty complex, so I didn't pursue it.

I can't judge the grammar and complexity issues, but as a potential user
it seems to me to be less complex to have multiple RETURNING clauses,
where I could inject my own constants about the specific actions, than
to have to deal with any of the suggested functions / clauses. More
repetitive, yes - but not more complex.

More importantly, I could add RETURNING to only some of the actions and
not always all at the same time - which seems pretty useful to me.

Best,

Wolfgang