[HBASE-6009] Changes for HBASE-5209 are technically incompatible

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Won't Fix
• Affects Version/s: 0.92.1, 0.94.0
• Component/s: master
• Hadoop Flags: Incompatible change, Reviewed

Release Note

HBASE-5209 was introduced in 0.92.1 and 0.94.0 but introduced an incompatibility from a 0.92.0 client. Since this had maded it into two releases already, we've decided to leave it in.

• Assignee: Unassigned
• Reporter: David S. Wang
• Created: 16/May/12 00:17
• Updated: 13/Jun/22 16:39
• Resolved: 25/Jun/12 21:56

Description

The additions to add backup masters to ClusterStatus are technically incompatible between clients and servers. Older clients will basically not read the extra bits that the newer server pushes for the backup masters, thus screwing up the serialization for the next blob in the pipe.

For the Writable, we can add a total size field for ClusterStatus at the beginning, or we can have start and end markers. I can make a patch for either approach; interested in whatever folks have to suggest. Would be good to get this in soon to limit the damage to 0.92.1 (don't know if we can get this in in time for 0.94.0).

Either change will make us forward-compatible starting with when the change goes in, but will not fix the backwards incompatibility, which we will have to mark with a release note as there have already been releases with this change.

Hopefully we can do this in a cleaner way when wire compat rolls around in 0.96.