[HIVE-1802] Encode MapReduce Shuffling Keys Differently for Single string/bigint Key

• Type: Improvement
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: Query Processor
• Assignee: Siying Dong
• Reporter: Siying Dong
• Created: 19/Nov/10 20:08
• Updated: 26/Jan/11 04:04

Description

Delimiters are not needed if we only have one shuffling key, and in the same time escaping delimiters are not needed. We can save some CPU time on serializing and shuffle slightly less amount of data to save memory footprint and network traffic.

Also there is a bug that for group-by, we by mistake add a -1 to the end of the key and pay one more unnecessary mem-copy. Can be easily fixed.