Re: Virtual generated columns

On Tue, 14 Jan 2025 at 13:37, Peter Eisentraut <peter(at)eisentraut(dot)org> wrote:
>
> Here is a new patch with that fixed and also a few
> tweaks suggested by Jian.
>

I'm hoping to push my RETURNING OLD/NEW patch [1] soon, so I thought
that I would check how it works together with this patch. The good
news is that AFAICS everything just works, and it's possible to return
old/new virtual generated columns in DML queries as expected.

It did require a minor update, because my patch adds a new
"result_relation" argument to ReplaceVarsFromTargetList() -- needed in
DML queries because, when propagating a Var's old/new
varreturningtype, replacement Vars need to be handled differently
depending on whether or not they refer to the result relation. So that
affects expand_generated_columns_internal(), when called from
fireRIRrules(). OTOH, from expand_generated_columns_in_expr() it's OK
to just pass 0 as the result relation index, because there won't be
any old/new Vars in an expression that's not part of a DML query.

Attached is the delta patch I used to handle this, along with a couple
of simple test cases. It doesn't really matter which feature makes it
in first, but the one that comes second will need to do something like
this.

Regards,
Dean

[1] https://commitfest.postgresql.org/51/4723/