What do "miscellaneous internal waits" mean in MemSQL studio?


#1

I used MemSQL Studio’s resource usage feature to to profile our cluster. A query that was running spent >90% of its time on “miscellaneous internal waits”. Is there a way to find out what these actually are?

2018-12-19%2016_57_51-MemSQL%20Studio


#2

“miscellaneous internal wait” time is technically the unaccounted time.

In practice, the unaccounted time is likely to be dominated by “inherent” waits for events and a good rule of thumb is to assume it’s not an indication of a problem. For example, time spent waiting for work dispatched to another thread to complete. We often do such dispatching for read queries, so it’s normal to see output like:

misc_wait

The row with high misc wait time is reporting on a thread which was waiting for per-partition threads to do real work.