Impala Aggregate Functions

Aggregate functions are a special category with different rules. These functions calculate a return value across all the items in a result set, so they require a FROM clause in the query:

select count(product_id) from product_catalog;
select max(height), avg(height) from census_data where age > 20;

Aggregate functions also ignore NULL values rather than returning a NULL result. For example, if some rows have NULL for a particular column, those rows are ignored when computing the AVG() for that column. Likewise, specifying COUNT(col_name) in a query counts only those rows where col_name contains a non-NULL value.

• APPX_MEDIAN Function

• AVG Function

• COUNT Function

• GROUP_CONCAT Function

• MAX Function

• MIN Function

• NDV Function

• STDDEV, STDDEV_SAMP, STDDEV_POP Functions

• SUM Function

• VARIANCE, VARIANCE_SAMP, VARIANCE_POP, VAR_SAMP, VAR_POP Functions

Parent topic: Impala Built-In Functions