On 3/28/23 06:55, Dominique Devienne wrote:
On Tue, Mar 28, 2023 at 3:23 PM Tom Lane <tgl@xxxxxxxxxxxxx
<mailto:tgl@xxxxxxxxxxxxx>> wrote:
Dominique Devienne <ddevienne@xxxxxxxxx
<mailto:ddevienne@xxxxxxxxx>> 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
It is part of the community contrib modules:
https://www.postgresql.org/docs/current/auto-explain.html
So install via whatever package system you are using. Or if building
from source build in the contrib/ directory.
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)
--
Adrian Klaver
adrian.klaver@xxxxxxxxxxx
