The error log in MariaDB 10.1 has entries like the following:
2016-05-11 14:50:00 140452469635200 [Note] /usr/sbin/mysqld: ready for connections.
What does "140452469635200" mean in this context? It is not documented here:
Is this the process ID, as added in this upstream patch?
Or is this some thread ID, as referenced in the MySQL 5.7 documentation?
As of MySQL 5.7.2, the ID included in error log messages is that of the thread within mysqld responsible for writing the message. This indicates which part of the server produced the message, and is consistent with general query log and slow query log messages, which include the connection thread ID. Before MySQL 5.7.2, the ID in error log messages is that of the mysqld process ID.