ORA-01415: too many distinct aggregate functions
Cause: The query contains more distinct aggregates than can be processed. The current limit is 255.
Action: Reduce the number of distinct aggregate functions in the query.
ORA-01415: too many distinct aggregate functions is an Oracle Database error. It is raised when the number of distinct aggregate functions that are referenced in a single statement exceeds the maximum allowed limit of 16.
Official Explanation: Oracle’s official explanation for this error is “The number of distinct aggregate functions specified in a single SELECT statement exceeds the maximum allowable limit of 16”.
Common Case: A SELECT statement has more than 16 different aggregate functions referenced inside.
Normal Handling: The following steps can be used to resolve this error:
1. Check the SELECT statement to verify the number of distinct aggregate functions referenced.
2. Replace any duplicate aggregate functions with non-aggregate functions, such as CASE or DECODE.
3. Limit the number of aggregate functions used in the SELECT statement to no more than 16.
4. If necessary, use WITH clause to split the SELECT statement into multiple parts.
5. Carefully test the changes made to the SELECT statement.