Re:Postgres Auditing in 150 lines of SQL
by netcraft on Wednesday March 09, 2022 @04:33PM
(#30620288)
we do that by setting a local variable before the query and then reading that in the triggers:
```
SET LOCAL foo.who_id = 'some-uuid';
UPDATE table
SET ...
``````
-- function to make getting the setting easier
DROP FUNCTION IF EXISTS get_who_id (text);
CREATE OR REPLACE FUNCTION get_who_id (default_value text DEFAULT null::text) RETURNS text AS $get_who_id$
DECLARE
who_id text;
BEGIN
BEGIN
who_id := current_setting('foo.who_id');
EXCEPTION
WHEN SQLSTATE '42704' THEN
RETURN default_value;
END;
IF (length(who_id) = 0) THEN
RETURN default_value;
END IF;
return who_id;
END
$get_who_id$ LANGUAGE plpgsql VOLATILE;
``````
CREATE OR REPLACE FUNCTION some_table_audit () RETURNS TRIGGER AS $some_table_audit$
DECLARE
who_id text;
BEGIN
who_id := get_who_id(null::text);
...
```Identifiers changed, but hopefully will give you the idea.
I've experiment with a very similar solution and it felt a bit dirty but so far it seems to be working just fine. I have made an integration for auditing with sqlmodel which I intend to share, but it is kind of rough and I was a bit stuck trying to clean it up. The idea is that you add e.g. a HeroHistory model derived from HeroBase and a HistoryMixin that creates the triggers and relationships to have an Audit log of the Hero table.
If anyone is interested give me a shout out
That's really interesting and gave me some (hopefully) good ideas.
Thank you very much!
PostgREST has an interesting approach to authentication that might give you some ideas:
https://postgrest.org/en/stable/auth.html
Supabase is built on top of PostgREST, but I can’t say for sure it uses the same means of authentication (I think it has its own Auth layer).
Re:Postgres Auditing in 150 lines of SQL
by oliverrice on Wednesday March 09, 2022 @04:38PM
(#30620361)
Supabase passes all the JWT info to postgrest so it is still available in transaction local config
Re:Postgres Auditing in 150 lines of SQL
by oliverrice on Wednesday March 09, 2022 @04:26PM
(#30620197)
if `user_id` is in the table you're auditing you could do
``` alter table audit.record_version add column user_id bigint default (coalesce(record, old_record) ->> 'user_id'); ```
or if you meant the SQL `current_user` you could extend the trigger to track it.
but if the user_id is only available in application space (not in the db) it will not be possible using straight SQL
Has anyone done something similar with SQL only?