variance aggregate function

Applies to: check marked yes Databricks SQL check marked yes Databricks Runtime

Returns the sample variance calculated from values of a group. This function is a synonym for var_samp aggregate function.

Syntax 

variance ( [ALL | DISTINCT] expr ) [FILTER ( WHERE cond ) ]

This function can also be invoked as a window function using the OVER clause.

Arguments

  • expr: An expression that evaluates to a numeric.

  • cond: An optional boolean expression filtering the rows used for aggregation.

Returns

A DOUBLE.

If DISTINCT is specified the function operates only on a unique set of expr values.

Examples 

> SELECT variance(col) FROM VALUES (1), (2), (3), (3) AS tab(col);
  0.9166666666666666

> SELECT variance(DISTINCT col) FROM VALUES (1), (2), (3), (3) AS tab(col);
 1.0