[USERGRID-1270] Enhance shard compaction to track the 'end' of a shard's valid Edges

• Type: Story
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.1.0
• Fix Version/s: 2.2.0
• Sprint: Usergrid 36
• Assignee: Michael Russo
• Reporter: Michael Russo
• Created: 18/Mar/16 22:20
• Updated: 24/Feb/17 22:56
• Resolved: 21/Mar/16 01:34

Description

During the shard compaction process, columns (edges) are moved from a source shard (row) to a target shard to balance the size against the configured shard size in Usergrid.

This causes tombstones to be created and can make seeks slower or potentially cause timeout exceptions in Astyanax if the tombstone overwhelming exception from Cassandra is thrown.

Implement the ability to 'mark' a shard's last valid edge so that can be fed into the range scan when retrieving the row (shard).