Re: Adding OLD/NEW support to RETURNING

On Mon, 11 Mar 2024 at 14:03, Dean Rasheed <dean.a.rasheed@gmail.com> wrote:
>
> Attached is an updated patch, fixing the seg-fault and now with
> support for foreign tables.
>

Updated version attached tidying up a couple of things and fixing another bug:

1). Tidied up the code in createplan.c that was testing for old/new
Vars in the returning list, by adding a separate function --
contain_vars_returning_old_or_new() -- making it more reusable and
efficient.

2). Updated the deparsing code for EXPLAIN so that old/new Vars are
always prefixed with the alias, so that it's possible to tell them
apart in the EXPLAIN output.

3). Updated rewriteRuleAction() to preserve the old/new alias names in
the rewritten query. I think this was only relevant to the EXPLAIN
output.

4). Fixed a bug in assign_param_for_var() -- this needs to compare the
varreturningtype of the Vars, otherwise 2 different Vars could get
assigned the same Param. As the comment said, this needs to compare
everything that _equalVar() compares, except for the specific fields
listed. Otherwise a subquery like (select old.a = new.a) in the
returning list would only generate one Param for the two up-level
Vars, and produce the wrong result.

5). Removed the ParseState fields p_returning_old and p_returning_new
that weren't being used anymore.

Regards,
Dean