org.apache.hadoop.hive.ql.parse.TableSample Maven / Gradle / Ivy
/**
* 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.parse;
import java.util.ArrayList;
/**
*
* This class stores all the information specified in the TABLESAMPLE clause.
* e.g. for the clause "FROM t TABLESAMPLE(1 OUT OF 2 ON c1) it will store the
* numerator 1, the denominator 2 and the list of expressions(in this case c1)
* in the appropriate fields. The afore-mentioned sampling clause causes the 1st
* bucket to be picked out of the 2 buckets created by hashing on c1.
*
*/
public class TableSample {
/**
* The numerator of the TABLESAMPLE clause.
*/
private int numerator;
/**
* The denominator of the TABLESAMPLE clause.
*/
private int denominator;
/**
* The list of expressions following ON part of the TABLESAMPLE clause. This
* list is empty in case there are no expressions such as in the clause
* "FROM t TABLESAMPLE(1 OUT OF 2)". For this expression the sampling is done
* on the tables clustering column(as specified when the table was created).
* In case the table does not have any clustering column, the usage of a table
* sample clause without an ON part is disallowed by the compiler
*/
private ArrayList exprs;
/**
* Flag to indicate that input files can be pruned.
*/
private boolean inputPruning;
/**
* Constructs the TableSample given the numerator, denominator and the list of
* ON clause expressions.
*
* @param num
* The numerator
* @param den
* The denominator
* @param exprs
* The list of expressions in the ON part of the TABLESAMPLE clause
*/
public TableSample(String num, String den, ArrayList exprs) {
numerator = Integer.valueOf(num).intValue();
denominator = Integer.valueOf(den).intValue();
this.exprs = exprs;
}
public TableSample(int num, int den) {
numerator = num;
denominator = den;
exprs = null;
}
/**
* Gets the numerator.
*
* @return int
*/
public int getNumerator() {
return numerator;
}
/**
* Sets the numerator.
*
* @param num
* The numerator
*/
public void setNumerator(int num) {
numerator = num;
}
/**
* Gets the denominator.
*
* @return int
*/
public int getDenominator() {
return denominator;
}
/**
* Sets the denominator.
*
* @param den
* The denominator
*/
public void setDenominator(int den) {
denominator = den;
}
/**
* Gets the ON part's expression list.
*
* @return ArrayList
*/
public ArrayList getExprs() {
return exprs;
}
/**
* Sets the expression list.
*
* @param exprs
* The expression list
*/
public void setExprs(ArrayList exprs) {
this.exprs = exprs;
}
/**
* Gets the flag that indicates whether input pruning is possible.
*
* @return boolean
*/
public boolean getInputPruning() {
return inputPruning;
}
/**
* Sets the flag that indicates whether input pruning is possible or not.
*
* @param inputPruning
* true if input pruning is possible
*/
public void setInputPruning(boolean inputPruning) {
this.inputPruning = inputPruning;
}
}