[HBASE-18649] Deprecate KV Usage in MR to move to Cells in 3.0

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.0.0-alpha-2
• Fix Version/s: 2.0.0-beta-1, 2.0.0
• Component/s: API, mapreduce
• Hadoop Flags: Incompatible change, Reviewed

Release Note

All the mappers and reducers output type will be now of MapReduceCell type. No more KeyValue type. How ever in branch-2 for compatibility we have allowed the older interfaces/classes that work with KeyValue to stay in the code base but they have been marked as deprecated.
The following interfaces/classes have been deprecated in branch-2
Import#KeyValueWritableComparablePartitioner
Import#KeyValueWritableComparator
Import#KeyValueWritableComparable
Import#KeyValueReducer
Import#KeyValueSortImporter
Import#KeyValueImporter
KeyValueSortReducer
KeyValueSerialization
WALPlayer#WALKeyValueMapper

So any existing MR jobs that is using the above public interfaces/classes will continue to work in branch-2 and the expected output value type of those mappers and reducers can continue to be KeyValue type.

In branch-3 the mappers and reducers output will only expect MapReduceCell as the type and will no longer work with KeyValue type.
The new public classes/interfaces added for branch-3 and in branch-2 are
CellSerialization
CellSortReducer
Import#CellWritableComparablePartitioner
Import#CellWritableComparable
Import#CellWritableComparator
Import#CellReducer
Import#CellSortImporter
Import#CellImporter
WALPlayer#WALCellMapper

• Assignee: ramkrishna.s.vasudevan
• Reporter: ramkrishna.s.vasudevan
• Created: 22/Aug/17 05:04
• Updated: 21/Mar/18 22:22
• Resolved: 04/Oct/17 10:33

Issue Links

• is related to: HBASE-18882 [TEST] Run MR branch-1 jobs against hbase2 cluster
• relates to: HBASE-10944 Remove all kv.getBuffer() and kv.getRow() references existing in the code
• links to: RB link