[KYLIN-1580] Use 1 byte instead of 8 bytes as column indicator in fact distinct MR job

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: v1.5.2
• Assignee: Shao Feng Shi
• Reporter: Shao Feng Shi
• Created: 13/Apr/16 02:49
• Updated: 26/May/16 09:16
• Resolved: 14/Apr/16 12:29

Description

One small enhancement in fact distinct job; today it uses 8 bytes in the head of the key to indicates the column index as well as cuboid id; actually it can be optimized to 1 byte for column index, and next 8 for cuboid id if the first is a special value; this will reduce the network IO between mappers and reducers.