[HBASE-12313] Redo the hfile index length optimization so cell-based rather than serialized KV key

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.99.2
• Component/s: regionserver, Scanners
• Hadoop Flags: Reviewed
• Assignee: Michael Stack
• Reporter: Michael Stack
• Created: 21/Oct/14 20:02
• Updated: 06/Apr/18 17:55
• Resolved: 29/Oct/14 18:37

Description

Trying to remove API that returns the 'key' of a KV serialized into a byte array is thorny.

I tried to move over the first and last key serializations and the hfile index entries to be cell but patch was turning massive. Here is a smaller patch that just redoes the optimization that tries to find 'short' midpoints between last key of last block and first key of next block so it is Cell-based rather than byte array based (presuming Keys serialized in a certain way). Adds unit tests which we didn't have before.

Also remove CellKey. Not needed... at least not yet. Its just utility for toString.