UserDefinedTableAggregateFunction (lenses-sql-udf 5.0.1 API)

All Superinterfaces:

UserDefinedAggregateFunction, UserDefinedFunction
```
public interface UserDefinedTableAggregateFunction
extends UserDefinedAggregateFunction
```
Interface for User Defined Table Aggregate Functions. Table-based aggregate functions need to provide a subtract method that handles removal of values.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`Value`	`subtract(Value aggregateKey, Value aggregatedValue, Value toBeSubtracted)`	Handles removal of a value from the aggregation.

Methods inherited from interface io.lenses.sql.udf.UserDefinedAggregateFunction
add, empty, finalStep, init, merge, typer

Methods inherited from interface io.lenses.sql.udf.UserDefinedFunction
name, owner, version

- Method Detail
  - subtract
```
Value subtract(Value aggregateKey,
               Value aggregatedValue,
               Value toBeSubtracted)
        throws UdfException
```
    Handles removal of a value from the aggregation.
    
    Parameters:
    
    aggregateKey - The key of the field being aggregated on.
    
    aggregatedValue - The current aggregated value.
    
    toBeSubtracted - The value to be subtracted from the current aggregated value.
    
    Returns:
    
    The updated aggregated value.
    
    Throws:
    
    UdfException - if the subtraction failed.