[SPARK-12913] Reimplement stat functions as declarative function

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 2.0.0
• Component/s: SQL
• Epic Link: Whole stage codegen
• Assignee: Davies Liu
• Reporter: Davies Liu
• Created: 19/Jan/16 23:15
• Updated: 02/Feb/16 19:50
• Resolved: 02/Feb/16 19:50

Description

As benchmarked and discussed here: https://github.com/apache/spark/pull/10786/files#r50038294.

Benefits from codegen, the declarative aggregate function could be much faster than imperative one, we should re-implement all the builtin aggregate functions as declarative one.

For skewness and kurtosis, we need to benchmark it to make sure that the declarative one is actually faster than imperative one.

Issue Links

• links to: [Github] Pull Request #10960 (davies)