Re: Oversight in reparameterize_path_by_child leading to executor crash

Richard Guo <guofenglinux(at)gmail(dot)com> writes:
> On Wed, Jan 31, 2024 at 5:12 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> * Why is it okay to just use pull_varnos on a tablesample expression,
>> when contain_references_to() does something different?

> Hmm, the main reason is that the expression_tree_walker() function does
> not handle T_RestrictInfo nodes. So we cannot just use pull_varnos or
> pull_var_clause on a restrictinfo list.

Right, the extract_actual_clauses step is not wanted for the
tablesample expression. But my point is that surely the handling of
Vars and PlaceHolderVars should be the same, which it's not, and your
v11 makes it even less so. How can it be OK to ignore Vars in the
restrictinfo case?

I think the code structure we need to end up with is a routine that
takes a RestrictInfo-free node tree (and is called directly in the
tablesample case) with a wrapper routine that strips the RestrictInfos
(for use on restriction lists).

> But I'm not sure about checking phinfo->ph_eval_at. It seems to me that
> the ph_eval_at could not overlap the other join relation; otherwise the
> clause would not be a restriction clause but rather a join clause.

At least in the tablesample case, plain Vars as well as PHVs belonging
to the other relation are definitely possible.

regards, tom lane