org.apache.flink.api.table.runtime

Class ExpressionFilterFunction<T>

java.lang.Object

org.apache.flink.api.common.functions.AbstractRichFunction

org.apache.flink.api.common.functions.RichFilterFunction<T>

org.apache.flink.api.table.runtime.ExpressionFilterFunction<T>

All Implemented Interfaces:

Serializable, FilterFunction<T>, Function, RichFunction

public class ExpressionFilterFunction<T>
extends RichFilterFunction<T>

Proxy function that takes an expression predicate. This is compiled upon runtime and calls to filter() are forwarded to the compiled code.

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
ExpressionFilterFunction(Expression predicate, CompositeType<T> inputType, TableConfig config)

Method Summary

Modifier and Type	Method and Description
FilterFunction<T>	compiledFilter()
boolean	filter(T in) The filter function that evaluates the predicate.
void	open(Configuration c) Initialization method for the function.

Methods inherited from class org.apache.flink.api.common.functions.AbstractRichFunction

close, getIterationRuntimeContext, getRuntimeContext, setRuntimeContext

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ExpressionFilterFunction

public ExpressionFilterFunction(Expression predicate,
                                CompositeType<T> inputType,
                                TableConfig config)

Method Detail

compiledFilter

public FilterFunction<T> compiledFilter()

open

public void open(Configuration c)

Description copied from interface: RichFunction

Initialization method for the function. It is called before the actual working methods (like map or join) and thus suitable for one time setup work. For functions that are part of an iteration, this method will be invoked at the beginning of each iteration superstep.

The configuration object passed to the function can be used for configuration and initialization. The configuration contains all parameters that were configured on the function in the program composition.

 public class MyMapper extends FilterFunction<String> {
 
     private String searchString;
     
     public void open(Configuration parameters) {
         this.searchString = parameters.getString("foo");
     }
     
     public boolean filter(String value) {
         return value.equals(searchString);
     }
 }
 

By default, this method does nothing.

Specified by:

open in interface RichFunction

Overrides:

open in class AbstractRichFunction

Parameters:

c - The configuration containing the parameters attached to the contract.

See Also:

Configuration

filter

public boolean filter(T in)

Description copied from interface: FilterFunction

The filter function that evaluates the predicate.

IMPORTANT: The system assumes that the function does not modify the elements on which the predicate is applied. Violating this assumption can lead to incorrect results.

Specified by:

filter in interface FilterFunction<T>

Specified by:

filter in class RichFilterFunction<T>

Parameters:

in - The value to be filtered.

Returns:

True for values that should be retained, false for values to be filtered out.