[HIVE-2068] Speed up query "select xx,xx from xxx LIMIT xxx" if no filtering or aggregation

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.8.0
• Component/s: Query Processor
• Hadoop Flags: Reviewed
• Assignee: Siying Dong
• Reporter: Siying Dong
• Created: 22/Mar/11 01:05
• Updated: 16/Dec/11 23:56
• Resolved: 19/Apr/11 18:18

Description

Currently, "select xx,xx from xxx where ...(only partition conditions) LIMIT xxx" will start a MapReduce job with input to be the whole table or partition. The latency can be huge if the table or partition is big. We could reduce number of input files to speed up the queries.