[SPARK-11850] Spark StdDev/Variance defaults are incompatible with Hive

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Not A Problem
• Affects Version/s: 1.6.0
• Component/s: SQL
• Assignee: Unassigned
• Reporter: Herman van Hövell
• Created: 19/Nov/15 10:20
• Updated: 19/Nov/15 19:25
• Resolved: 19/Nov/15 18:56

Description

The stddev and variance functions currently defaults to the 'sample' version whereas Hive uses the 'population' version for this. See:

• https://cwiki.apache.org/confluence/display/Hive/LanguageManual+UDF#LanguageManualUDF-Built-inAggregateFunctions(UDAF)
• https://github.com/apache/spark/blob/master/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/FunctionRegistry.scala#L192-L196

Is this on purpose? Or by accident?

Issue Links

• is related to: SPARK-11490 variance should alias var_samp instead of var_pop