Update ddl.sql

[hellower]

client_pid(worker_pid)

The server running pg_timetable may be different, but coincidentally the pid may be the same.
At my docker enviroment, serveral same pid(differnt docker constainer) happended.

Duplicate execution can be prevented by adding the client_addr column as shown below.

SQL> select * from timetable.active_sessions
client_id

---

14 pg_timetable 28417 167.71.214.34 2022-08-07 14:12:24.333 +0900
14 pg_timetable 28418 167.71.214.34 2022-08-07 14:12:24.366 +0900
14 pg_timetable 28422 128.199.132.200 2022-08-07 14:12:29.563 +0900
14 pg_timetable 28423 128.199.132.200 2022-08-07 14:12:29.589 +0900

[pashagolub]

Thanks for the PR. It makes sense. On the other hand, these issues must be addressed before:

• update timetable.log table, since it holds the pid column as well;
• same goes for timetable.execution_log;
• all changes to the DB schema should be implemented as a new migration

[pashagolub]

What if we run several instances on the same host? Then inet client addr will be the same

[hellower]

s.client_addr <> inet_client_addr()
AND s.client_name = worker_name # !!!!

If there are multiple instances on the same host, each clientname must be unique.

............ config.yaml 
# clientname:                    Unique name for application instance
clientname: pg_scheduler

..... bootstrap.go 
sql := fmt.Sprintf("SELECT timetable.try_lock_client_name(%d, $worker$%s$worker$)", os.Getpid(), pge.ClientName)

[pashagolub]

The client name must be absolutely unique, even if your workers are running on different hosts.

[pashagolub]

And that, in turn, means we have a bug that must be fixed immediately. 🤔

[pashagolub]

To prove this fix won't prevent a bug, you can try to start several docker containers, e.g.

$ docker run -d --rm cybertecpostgresql/pg_timetable:latest postgresql://<conn_str> -c worker001
5b1ab3ad6bd585db05f88130bb78f1418ac57ab3b1c8a755703017dc4ff486da

$ docker run -d --rm cybertecpostgresql/pg_timetable:latest postgresql://<conn_str> -c worker001
4de31c35c0226d89ef9100324e611e7caad27a9ac30fc588c54263036597137f

$ docker run -d --rm cybertecpostgresql/pg_timetable:latest postgresql://<conn_str> -c worker001
b0767832353589529d69f36f04b9ee14a25d14d8e796b8bf0bbae467a5e280de

$ psql

timetable=>SELECT *
FROM timetable.active_session s
        WHERE
            s.client_name = 'worker001';

client_pid|client_name|server_pid|started_at                   |
----------+-----------+----------+-----------------------------+
         1|worker001  |     27596|2022-08-15 14:12:39.333 +0200|
         1|worker001  |     26052|2022-08-15 14:12:39.565 +0200|
         1|worker001  |     24348|2022-08-15 14:12:58.131 +0200|
         1|worker001  |     18848|2022-08-15 14:12:58.245 +0200|
         1|worker001  |     26692|2022-08-15 14:40:06.516 +0200|
         1|worker001  |      8620|2022-08-15 14:40:06.713 +0200|

[pashagolub]

Thanks for your help! Superseded by #476

[hellower]

Thank you!