Re: MERGE and parsing with prepared statements

On Fri, Jul 15, 2022 at 11:40 AM Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>
wrote:

> On 2022-Jul-15, Justin Pryzby wrote:
>
> > It seems a bit odd that it's impossible to use merge with prepared
> statements
> > without specifically casting the source types (which I did now to
> continue my
> > experiment).
>
> I have no comments on this. Maybe it can be improved, but I don't know
> how.
>
>
Not tested, but the example prepare command fails to make use of the
optional data types specification. Using that should remove the need to
cast the parameter placeholder within the query itself.

That said, in theory the INSERT specification of the MERGE could be used to
either resolve unknowns or even forcibly convert the data types of the
relation produced by the USING clause to match the actual types required
for the INSERT (since that will happen at insert time anyway). This would
make the UPDATE behavior slightly different than a top-level UPDATE command
though, since that does not have the same context information.

David J.