OMFG I don't even know where to start..
Probably should start with last week (as this is the first time I had to deal with this problem directly)..

Also please note that all packages, procedure/function names, tables etc have fictional names, so every similarity between this story and reality is just a coincidence!!

Here it goes..

Lat week we implemented a new feature for the customer on production, everything was working fine.. After a day or two, the customer notices the audit logs are not complete aka missing user_id or have the wrong user_id inserted.
Hm.. ok.. I check logs (disk + database).. WTF, parameters are being sent in as they should, meaning they are there, so no idea what is with the missing ids.

OK, logs look fine, but I notice user_id have some weird values (I already memorized most frequent users and their ids). So I go check what is happening in the code, as the procedures/functions are called ok.

Wow, boy was I surprised.. many many times..
In the code, we actually check for user in this apps db or in case of using SSO (which we were) in the main db schema..
The user gets returned & logged ok, but that is it. Used only for authentication. When sending stuff to the db to log, old user Id is used, meaning that ofc userid was missing or wrong.

Anyhow, I fix that crap, take care of some other audit logs, so that proper user id was sent in. Test locally, cool. Works. Update customer's test servers. Works. Cool..

I still notice something off.. even though I fixed the audit_dbtable_2, audit_dbtable_1 still doesn't show proper user ids.. This was last week. I left it as is, as I had more urgent tasks waiting for me..

Anyhow, now it came the time for this fuckup to be fixed. Ok, I think to myself I can do this with a bit more hacking, but it leaves the original database and all other apps as is, so they won't break.
I crate another pck for api alone copy the calls, add user_id as param and from that on, I call other standard functions like usual, just leave out the user_id I am now explicitly sending with every call.
Ok this might work.

I prepare package, add user_id param to the calls.. great, time to test this code and my knowledge..

I made changes for api to incude the current user id (+ log it in the disk logs + audit_dbtable_1), test it, and check db..
Disk logs fine, debugging fine (user_id has proper value) but audit_dbtable_1 still userid = 0.

WTF?! I go check the code, where I forgot to include user id.. noup, it's all there. OK, I go check the logging, maybe I fucked up some parameters on db level. Nope, user is there in the friggin description ON THE SAME FUCKING TABLE!!
Just not in the column user_id...

WTF..Ok, cig break to let me think..

I come back and check the original auditing procedure on the db.. It is usually used/called with null as the user id. OK, I have replaced those with actual user ids I sent in the procedures/functions. Recheck every call!! TWICE!! Great.. no fuckups. Let's test it again!
OFC nothing changes, value in the db is still 0. WTF?! HOW!?

So I open the auditing pck, to look the insides of that bloody procedure.. WHAT THE ACTUAL FUCK?!
Instead of logging the p_user_sth_sth that is sent to that procedure, it just inserts the variable declared in the main package..
WHAT THE ACTUAL FUCK?! Did the 'new guy' made changes to this because he couldn't figure out what is wrong?! Nope, not him. I asked the CEO if he knows anything.. Noup.. I checked all customers dbs (different customers).. ALL HAD THIS HARDOCED IN!!! FORM THE FREAKING YEAR 2016!!! O.o

Unfuckin believable.. How did this ever work?!

Looks like at the begining, someone tried to implement this, but gave up mid implementation.. Decided it is enough to log current user id into BLABLA variable on some pck..
Which might have been ok 10+ years ago, but not today, not when you use connection pooling.. FFS!!

So yeah, I found easter eggs from years ago.. Almost went crazy when trying to figure out where I fucked this up. It was such a plan, simple, straight-forward solution to auditing..

If only the original procedure was working as it should.. bloddy hell!!