Re: BUG #19037: Planner fails on estimating array length with "no relation entry" error

On Wed, Sep 3, 2025 at 12:27 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Richard Guo <guofenglinux(at)gmail(dot)com> writes:
> > Here is the patch that passes root as NULL to cost_qual_eval() in
> > cost_subplan(), along with some commentary about why.

> v2 LGTM. I did think of a way to make the test case a little
> less busy-looking:
>
> select (1 = any(array_agg(f1))) = any (select false) from int4_tbl;
>
> but that's just cosmetic.

Thanks, I'll take this test case.

One thing I'm not quite sure about is whether we should backpatch this
fix to pre-v17 branches. Prior to v17, estimate_array_length() wasn't
taught to use statistics, so this error isn't reproducible there.
OTOH, passing a root without a valid simple_rel_array to
cost_qual_eval() still seems potentially unsafe. What do you think?

- Richard