/**
* 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.exec.vector.keyseries;
import java.io.IOException;
import org.apache.hadoop.hive.ql.exec.vector.VectorizedRowBatch;
/**
* An abstraction of keys within a VectorizedRowBatch.
*
* A key is one or more columns.
*
* When there is a sequential "run" of equal keys, they are collapsed and represented by a
* duplicate count.
*
* The batch of keys (with sequential duplicates collapsed) is called a series.
*
* A key can be all null, or a key with no or some nulls.
*
* All keys have a duplicate count.
*
* A key with no or some nulls has:
* 1) A hash code.
* 2) Key values and other value(s) defined by other interfaces.
*
* The key series is logically indexed. That is, if batch.selectedInUse is true, the indices
* will be logical and need to be mapped through batch.selected to get the physical batch
* indices. Otherwise, the indices are physical batch indices.
*/
public interface VectorKeySeries {
/**
* Process a non-empty batch of rows and compute a key series.
*
* The key series will be positioned to the beginning.
*
* @param batch
* @throws IOException
*/
void processBatch(VectorizedRowBatch batch) throws IOException;
/**
* Position to the beginning of the key series.
*/
void positionToFirst();
/**
* @return the current logical index of the first row of the current key.
* The next duplicate count rows have the same key.
*/
int getCurrentLogical();
/**
* @return true when the current key is all nulls.
*/
boolean getCurrentIsAllNull();
/**
* @return the number of duplicate keys of the current key.
*/
int getCurrentDuplicateCount();
/**
* @return true when there is at least one null in the current key.
* Only valid when getCurrentIsAllNull is false. Otherwise, undefined.
*/
boolean getCurrentHasAnyNulls();
/**
* @return the hash code of the current key.
* Only valid when getCurrentIsAllNull is false. Otherwise, undefined.
*/
int getCurrentHashCode();
/**
* Move to the next key.
* @return true when there is another key. Otherwise, the key series is complete.
*/
boolean next();
}