[APLO-280] Clarification about message groups

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.6
• Assignee: Hiram R. Chirino
• Reporter: Lionel Cons
• Created: 17/Dec/12 07:24
• Updated: 21/May/14 15:01
• Resolved: 07/Feb/13 19:10

Description

First, there is a typo in the added doc as it contains "When you another subscription to a queue".

Then, it seems there is a contradiction between "ensures that all messages for the same message group will be sent to the same consumer" and "the broker rebalances the message groups across consumers".

Apollo has no way to know if new messages for an already seen message group will continue to come or not. So, by rebalancing, it may cause new messages of the same group to go to another consumer.

IMHO, rebalancing can only happen safely when old consumers stop and only for their "attached" message groups.