Do this before the patch is applied and compare it to after Setup Edit postgresql.conf to set up the slowlog to log all db queries, eg in /etc/postgresql/10/main/postgresql.conf file set  log_min_duration_statement = 0 Restart your PostgreSQL server for the config changes to take effect. E.g. "sudo service postgresql restart" Copy the test script testpg.php to your Moodle root folder. Open a separate terminal window and tail the Postgres logs. e.g. for PostgreSQL 10 in Ubuntu: tail -f /var/log/postgresql/postgresql-10-main.log Before patch test Run the test script. php testpg.php Run it 2-3 times to make sure everything is warm and stable. You'll see the following logs every time you run the test script. LOG: duration: 3.448 ms statement: select oid,typname from pg_type On the log window press enter a couple of times to make space and distinguish the new logs from the old logs. After patch test On the log window press enter a couple of times to make space and distinguish the new logs from the old logs. Run the test script again You'll see the following log on your first test script run after the patch. LOG: duration: 3.448 ms statement: select oid,typname from pg_type Run the test script again for 2 or 3 more times. Make sure you press enter a couple of times each time you run the test script to distinguish new logs. Confirm that you don't see the following log in the subsequent runs. LOG: duration: 3.448 ms statement: select oid,typname from pg_type