Re: Where to store some session based info? - Mailing list pgsql-general

From Pavel Stehule
Subject Re: Where to store some session based info?
Date
Msg-id CAFj8pRCTfHpwesLvF0jVsqEfuLv65WSXaiR-21bmUJEo7jceNQ@mail.gmail.com
Whole thread Raw
In response to Where to store some session based info?  (Durumdara <durumdara@gmail.com>)
List pgsql-general
Hi

st 25. 3. 2026 v 18:21 odesílatel Durumdara <durumdara@gmail.com> napsal:
Hello!

Sometimes we have to use "Current User ID", and "User Name" in the Triggers to make a log into a table. These values are based on our User, not in the PSQL role.

Now we use a temporary table to do this.
When the user logged into the application, we created a temporary table with the same name (user_info) and structure. This holds the data (id, name, machine info, ip address).

In the trigger we try to find this table (in the LOCAL_TEMPORARY schema).
Then we read the row into a JSON record, and then into PLPGSQL variables.
Tables can exist with the same name, so this is the safest solution.
If the User  ID is invalid (none or empty) that means this is a background operation, and then we don't need to log the changes.

But maybe there is a better way to somehow store some session based data and use it in the triggers. 
Because if these selects are slow, the trigger is also slow. So when I start an UPDATE command in a big table, maybe this slows down the whole operation.

Note:
A table with the PID key is not enough, because the PID is a repeated value.
I logged it and in the Windows system there are many of the same values (10001, 10004, etc.).
Ok, I can combine with session creation time. But for this I also need to start a select in the pg_stat_activty table.

So maybe you have an easier way to point to a record in a session.
Important: the PG servers are different, the lesser version is 11, and we have only a Database Owner role. We can't configure the server.

What is your opinion? Is there any way to get session based data?
As I read before, we can't set the session variables onfly.

There are not native session variables, but you can use workaround - custom setting

(2026-03-25 18:39:04) postgres=# set myvar.xxx to 'hello';
select current_setting('myvar.xxx');
SET
┌─────────────────┐
│ current_setting │
╞═════════════════╡
│ hello           │
└─────────────────┘
(1 row)

Regards

Pavel
 

Best regards
dd


pgsql-general by date:

Previous
From: Durumdara
Date:
Subject: Where to store some session based info?
Next
From: Adrian Klaver
Date:
Subject: Re: Where to store some session based info?