How to set and get the current application name using SQL query in PostgreSQL?

I have an application that uses Advantage Database Server. I want to migrate this application to PostgreSQL. To set the name of the application that established a connection to the database, I use the sp_SetApplicationID(ApplicationID) procedure.

EXECUTE PROCEDURE sp_SetApplicationID(:appname);

To get the application name, I use the sp_GetApplicationID() procedure.

EXECUTE PROCEDURE sp_GetApplicationID();

Is there such a possibility in PostgreSQL?

For example, if I run the following sql query in PostgreSQL, I will see application_name of all connections to the database. There can be many connections.

SELECT * FROM pg_stat_activity;

But I don't know how to change application_name for the current connection using SQL query. And can I get the application_name back. Maybe there is another way?

Solution

You should to use command set or function set_config

(2024-12-28 17:43:56) postgres=# set application_name to 'pokus';
SET
(2024-12-28 17:44:04) postgres=# \x
Expanded display is on.
(2024-12-28 17:44:06) postgres=# select * from pg_stat_activity where application_name = 'pokus';
┌─[ RECORD 1 ]─────┬──────────────────────────────────────────────────────────────────┐
│ datid            │ 5                                                                │
│ datname          │ postgres                                                         │
│ pid              │ 1177765                                                          │
│ leader_pid       │ ∅                                                                │
│ usesysid         │ 16384                                                            │
│ usename          │ pavel                                                            │
│ application_name │ pokus                                                            │
│ client_addr      │ ∅                                                                │
│ client_hostname  │ ∅                                                                │
│ client_port      │ -1                                                               │
│ backend_start    │ 2024-12-28 17:43:56.311933+01                                    │
│ xact_start       │ 2024-12-28 17:44:21.922268+01                                    │
│ query_start      │ 2024-12-28 17:44:21.922268+01                                    │
│ state_change     │ 2024-12-28 17:44:21.92227+01                                     │
│ wait_event_type  │ ∅                                                                │
│ wait_event       │ ∅                                                                │
│ state            │ active                                                           │
│ backend_xid      │ ∅                                                                │
│ backend_xmin     │ 758                                                              │
│ query_id         │ ∅                                                                │
│ query            │ select * from pg_stat_activity where application_name = 'pokus'; │
│ backend_type     │ client backend                                                   │
└──────────────────┴──────────────────────────────────────────────────────────────────┘

(2024-12-28 17:45:50) postgres=# select set_config('application_name', 'pokus', false);
┌────────────┐
│ set_config │
╞════════════╡
│ pokus      │
└────────────┘
(1 row)

(2024-12-28 17:45:54) postgres=# show application_name ;
┌──────────────────┐
│ application_name │
╞══════════════════╡
│ pokus            │
└──────────────────┘
(1 row)