/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.hive.ql.udf.generic;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.typeinfo.TypeInfo;
/**
* A callback interface used in conjunction with <tt>GenericUDAFResolver2</tt>
* interface that allows for a more extensible and flexible means of
* discovering the parameter types provided for UDAF invocation. Apart from
* allowing the function implementation to discover the <tt>TypeInfo</tt> of
* any types provided in the invocation, this also allows the implementation
* to determine if the parameters were qualified using <tt>DISTINCT</tt>. If
* no parameters were specified explicitly, it allows the function
* implementation to test if the invocation used the wildcard syntax
* such as <tt>FUNCTION(*)</tt>.
* <p>
* <b>Note:</b> The implementation of function does not have to handle the
* actual <tt>DISTINCT</tt> or wildcard implementation. This information is
* provided only to allow the function implementation to accept or reject
* such invocations. For example - the implementation of <tt>COUNT</tt> UDAF
* requires that the <tt>DISTINCT</tt> qualifier be supplied when more than
* one parameters are specified in the invocation. The actual filtering of
* data bound to parameter types for <tt>DISTINCT</tt> implementation is
* handled by the framework and not the <tt>COUNT</tt> UDAF implementation.
*/
public interface GenericUDAFParameterInfo {
/**
*
* @return the parameter type list passed into the UDAF.
*/
@Deprecated
TypeInfo[] getParameters();
/**
*
* @return getParameters() with types returned as ObjectInspectors.
*/
ObjectInspector[] getParameterObjectInspectors();
/**
* Returns <tt>true</tt> if the UDAF invocation was qualified with
* <tt>DISTINCT</tt> keyword. Note that this is provided for informational
* purposes only and the function implementation is not expected to ensure
* the distinct property for the parameter values. That is handled by the
* framework.
* @return <tt>true</tt> if the UDAF invocation was qualified with
* <tt>DISTINCT</tt> keyword, <tt>false</tt> otherwise.
*/
boolean isDistinct();
/**
* The flag to indicate if the UDAF invocation was from the windowing function
* call or not.
* @return <tt>true</tt> if the UDAF invocation was from the windowing function
* call.
*/
boolean isWindowing();
/**
* Returns <tt>true</tt> if the UDAF invocation was done via the wildcard
* syntax <tt>FUNCTION(*)</tt>. Note that this is provided for informational
* purposes only and the function implementation is not expected to ensure
* the wildcard handling of the target relation. That is handled by the
* framework.
* @return <tt>true</tt> if the UDAF invocation was done with a wildcard
* instead of explicit parameter list.
*/
boolean isAllColumns();
}