[HIVE-2121] Input Sampling By Splits

• Type: New Feature
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.8.0
• Component/s: Query Processor
• Hadoop Flags: Reviewed
• Release Note: This patch adds support for the 'TABLESAMPLE(x PERCENT)' clause.
• Assignee: Siying Dong
• Reporter: Siying Dong
• Created: 20/Apr/11 00:26
• Updated: 15/Jun/12 19:17
• Resolved: 29/Apr/11 22:51

Description

We need a better input sampling to serve at least two purposes:
1. test their queries against a smaller data set
2. understand more about how the data look like without scanning the whole table.
A simple function that gives a subset splits will help in those cases. It doesn't have to be strict sampling.