Looking at the QLAFilter log rotation implementation, it relies on a constant stream of queries to properly rotate the file. This would mean that if a system is completely idle and a log rotation is done, the qlafilter would not rotate the logs.

The fact that the logs are rotated with maxctrl rotate logs isn't documented in the filter documentation. This should be documented along with the fact that the rotation will only take place when the next message is written.

The problem here seems to have been different, messages were written before the rotation, but after rotation with maxctrl rotate logging just stopped. The logfaile stayed at 0 byte size even though further entries should have happened ...

Could be related to MXS-3113.

To test whether this is simply a symptom of MXS-3113, you could toggle the high-precision logging to force a log message to be generated. You can do this with the following commands:

maxctrl alter logging highprecision true

maxctrl alter logging highprecision false

This should cause messages like this to be logged:

2020-08-20 14:46:46.460   notice : highprecision logging is enabled.

2020-08-20 14:46:47   notice : highprecision logging is disabled.

Closing this as potentially fixed by MXS-3113. hholzgra if you manage to reproduce this with the latest releases, please let us know and we'll reopen this issue.