Use of Message Groups

[Martin Lichtin <li...@yahoo.com.INVALID>]

Wanted to ask some specifics about the "Message Groups" feature.

  * is the feature incurring an overhead to the broker processing?
  * would a large queue depth cause any issues?
  * there is a note about 'grouping in memory', does this mean messsages are somehow re-ordered?
  * would an ever increasing number of groups, e.g. a new group for every 2nd or 3rd message cause an issue?

Then also I wanted to ask about a specific use case:
There is a way to close a group. Is there also one to explicitly open a group?
I have a situation where a certain consumer should attract a specific group, can I tell the broker about this in advance?

Thanks - Martin