[BOOKKEEPER-606] Scale Subscriptions

• Type: New Feature
• Status: Resolved
• Priority: Major
• Resolution: Won't Fix
• Affects Version/s: 4.2.0, 4.2.1
• Component/s: hedwig-client, hedwig-server
• Assignee: Unassigned
• Reporter: Jiannan Wang
• Created: 15/Apr/13 13:11
• Updated: 16/Mar/16 04:21
• Resolved: 16/Mar/16 04:21

Description

At present, Hedwig is able to scale topic but not subscription, so one topic can only serve a few subscribers. However, there are many user cases with huge subscriptions in reality: lots of users are interested in same things, such as specific sport game, famous people's activity (update on twitter/facebook), etc.

And if Hedwig user plans to scale subscriptions, the only way I know is transform subscription into topic: for each subscription, create a new topic "topic#subId" then each topic consists of only one subscriber. It do resolve the scalability issue but it is not an ideal solution:

• Topic amount grows a lot, which increases the metadata usage and demands more Hub servers.
• Each message is replicated for each subscriber. In other words, assume there are S subscribers with M messages on the topic, then the actual message number in the system is S x M!

This JIRA aims to find a better solution for Hedwig to afford subscription scalability.