Re: RETURNING syntax for COPY

On 08.05.2013 19:44, Tom Lane wrote:
> Karol Trzcionka<karlikt(at)gmail(dot)com> writes:
>> as a continuation of my proposal expanding RETURNING syntax by
>> AFTER/BEFORE, there can be enough time to implement RETURNING for COPY.
>
> No there isn't; what you suggest would require FE/BE protocol
> extensions, making it several orders of magnitude more work than the
> other thing.

I'd imagine that the flow would go something like this:

BE FE

CopyInResponse
CopyData
CopyData
...
CopyDone
RowDescription
DataRow
DataRow
CommandComplete

A well-written client should be able to handle that. But if one expects
the backend to always send a CommandComplete after CopyDone, it will get
confused. Implementing that doesn't seem too difficult to me.

I agree that this is much more work than the UPDATE RETURNING
BEFORE/AFTER, though. Not sure if that's a good or a bad thing.

- Heikki