Re: Plans for ON DELETE CASCADE? Which index is used, if at all?

On Tue, Mar 28, 2023 at 3:23 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Dominique Devienne <ddevienne(at)gmail(dot)com> writes:
> > Hi. Given the classical parent/child schema below, with an ON DELETE
> > CASCADE FK constraint, I'd like to know which index is used (if any) to
> > delete child rows affected by the CASCADE.
>
> > But explain (analyze) does not give me that.
>
> Yeah, it will just report the time spent in the FK triggers,
> not what they were doing exactly.
>
> IIRC, you can see the CASCADE operations with contrib/auto_explain,
> if you enable auto_explain.log_nested_statements.
>

Thanks. Looks like this won't be easily available to me :(. --DD

dd=> select * from pg_available_extensions where name like '%auto%';
name | default_version | installed_version | comment
---------+-----------------+-------------------+---------------------------------------
autoinc | 1.0 | | functions for
autoincrementing fields
(1 row)

dd=> select * from pg_available_extensions where name like '%explain%';
name | default_version | installed_version | comment
------+-----------------+-------------------+---------
(0 rows)