Re: Oversight in reparameterize_path_by_child leading to executor crash

On 23/8/2023 12:37, Richard Guo wrote:
> If we go with the "tablesample scans can't be reparameterized" approach
> in the back branches, I'm a little concerned that what if we find more
> cases in the futrue where we need modify RTEs for reparameterization.
> So I spent some time seeking and have managed to find one: there might
> be lateral references in a scan path's restriction clauses, and
> currently reparameterize_path_by_child fails to adjust them.
It may help you somehow: in [1], we designed a feature where the
partitionwise join technique can be applied to a JOIN of partitioned and
non-partitioned tables. Unfortunately, it is out of community
discussions, but we still support it for sharding usage - it is helpful
for the implementation of 'global' tables in a distributed
configuration. And there we were stuck into the same problem with
lateral relids adjustment. So you can build a more general view of the
problem with this patch.

[1] Asymmetric partition-wise JOIN
https://www.postgresql.org/message-id/flat/CAOP8fzaVL_2SCJayLL9kj5pCA46PJOXXjuei6-3aFUV45j4LJQ%40mail.gmail.com

--
regards,
Andrey Lepikhov
Postgres Professional