org.h2.expression.AggregateData Maven / Gradle / Ivy
/*
* Copyright 2004-2014 H2 Group. Multiple-Licensed under the MPL 2.0,
* and the EPL 1.0 (http://h2database.com/html/license.html).
* Initial Developer: H2 Group
*/
package org.h2.expression;
import org.h2.engine.Database;
import org.h2.value.Value;
/**
* Abstract class for the computation of an aggregate.
*/
abstract class AggregateData {
/**
* Create an AggregateData object of the correct sub-type.
*
* @param aggregateType the type of the aggregate operation
* @return the aggregate data object of the specified type
*/
static AggregateData create(int aggregateType) {
if (aggregateType == Aggregate.SELECTIVITY) {
return new AggregateDataSelectivity();
} else if (aggregateType == Aggregate.GROUP_CONCAT) {
return new AggregateDataGroupConcat();
} else if (aggregateType == Aggregate.COUNT_ALL) {
return new AggregateDataCountAll();
} else if (aggregateType == Aggregate.COUNT) {
return new AggregateDataCount();
} else if (aggregateType == Aggregate.HISTOGRAM) {
return new AggregateDataHistogram();
} else {
return new AggregateDataDefault(aggregateType);
}
}
/**
* Add a value to this aggregate.
*
* @param database the database
* @param dataType the datatype of the computed result
* @param distinct if the calculation should be distinct
* @param v the value
*/
abstract void add(Database database, int dataType, boolean distinct, Value v);
/**
* Get the aggregate result.
*
* @param database the database
* @param dataType the datatype of the computed result
* @param distinct if distinct is used
* @return the value
*/
abstract Value getValue(Database database, int dataType, boolean distinct);
}