[PHOENIX-6125] Make sure SYSTEM.TASK does not split

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 5.0.0, 4.15.0
• Fix Version/s: 5.1.0, 4.16.0

Release Note

We have new split policy introduced for SYSTEM.TASK which for now is just extending DisabledRegionSplitPolicy. As part of an upgrade to 4.16/5.1, updating split policy will be taken care of unless it was already updated manually.

Hence, before 4.16/5.1 upgrade, if operator has already manually updated split policy of SYSTEM.TASK, an exception will be thrown during upgrade to 4.16/5.1 which would mandate an operator intervention to perform:

1. Merging SYSTEM.TASK regions into one single region (if multiple regions were already available before 4.16/5.1 upgrade)
2. Remove split policy of the table manually.

• Assignee: Viraj Jasani
• Reporter: Chinmay Kulkarni
• Created: 11/Sep/20 22:14
• Updated: 02/Nov/20 16:31
• Resolved: 19/Oct/20 18:55

Description

To avoid problems such as PHOENIX-5945 we can just prevent SYSTEM.TASK from splitting.

Currently we only store relatively rare tasks inside SYSTEM.TASK and so we should probably be safe to assume that it only spans a single region. Note that we will also have to handle changing the split policy during the upgrade path for 4.15 operators.

Issue Links

• fixes: PHOENIX-5945 TaskRegionObserver can kick off the same task multiple times if SYSTEM.TASK has split
• is depended upon by: PHOENIX-5945 TaskRegionObserver can kick off the same task multiple times if SYSTEM.TASK has split
• links to: GitHub Pull Request #923