Limiting annotation depth in CalQL

This is more of a question than issue report. Is there a way to limit the depth of annotations in CalQL? So for instance if I have:
```
annotation mpi.rank time.offset time.inclusive.duration
main
main/foo
main/foo/bar
main/foo
main/foo/baz
main/foo
main
...
```

And I want to print out only sum total time for main and main/foo, is there some magic argument to achieve this? I guess one way to express this is to limit the depth, but another way would be to explicitly specify annotation prefixes I'm interested in.

If not, perhaps this is a feature request after all.

Start with the CalQL entry point and review how annotation records are selected and aggregated. Determine whether depth limits or annotation-prefix filters are supported, then define the expected output for the example so the requested behavior can be tested.

Written by the indexing model from the issue text.