Στις 10/9/24 20:22, ο/η Laurenz Albe έγραψε:
On Tue, 2024-09-10 at 12:20 +0300, Achilleas Mantzios - cloud wrote:
On 9/10/24 00:09, Laurenz Albe wrote:
On Mon, 2024-09-09 at 16:14 +0300, Achilleas Mantzios - cloud wrote:
The below runs on PostgreSQL 16.4
We are trying to implement a certain operation based on a security definer
function : mariner_update_availability_date
This is supposed to update a table : mariner , which has several other triggers :
[...] zzzmariner_dmq_tg AFTER INSERT OR DELETE OR UPDATE ON mariner DEFERRABLE INITIALLY DEFERRED FOR EACH ROW EXECUTE FUNCTION export_dmq()
As you noticed the last trigger is a CONSTRAINT DEFERRABLE trigger.
This function mariner_update_availability_date is supposed to be run by a user :
cbt_results_import stripped of any privileges to the rest of the system. Here is
what we get : when we SET the constraint of the last trigger to IMMEDIATE, the
function runs on behalf of its owner (postgres) who has all needed privileges
(as superuser) to run the update on mariner table and also run the triggers .
However, when we run with this CONSTRAINT as DEFERRED then it seems to NOT run
the last deferrable trigger as postgres.
I have proposed a patch that fixes exactly that case:
https://commitfest.postgresql.org/49/4888/
So far, the feedback seems to be that it is not considered a bug.
But that doesn't mean that we cannot change the behavior.
Nice work! However I am not sure. What's a trigger owner btw in the
thread :
? Do they mean the table owner? is the trigger creator / owner stored
somewhere ? I dont see it in system tables or the schema dump. Or do
they imply the trigger function owner ?
The owner of a trigger is always the owner of the table.
Thank you.
Maybe controlling the queued and later executed trigger invocations
security context via a new special GUC? such as :
trigger_security_ctx = current_user (default) | table/trigger_owner |
execution_triggered_user
(in every case a SECURITY DEFINER function would override the above setting)
The PostgreSQL project has made bad experiences with parameters that change
the semantics of SQL statements, so I think that idea will meet resistance.
Besides, what I am proposing in the patch is not to use the owner of the
table, but the current_user at the time that the trigger is queued.
Yes, your patch "
current_user at the time that the trigger is queued " is my
execution_triggered_user from above. Bad naming from my part.
I had the impression that that is what you are looking for.
To be frank, the current behavior albeit confusing to noobs, (and I have no excuses here using PostgreSQL since 2001 in this same job) , seems right to me. So I would welcome some kind of GUC/session-level or DDL/object-level control but still the current behavior is fine to live with.
Executing as table owner can easily be done with a SECURITY DEFINER function.
Yours,
Laurenz Albe
--
Achilleas Mantzios IT DEV - HEAD IT DEPT Dynacom Tankers Mgmt (as agents only)
