Bug 180189 Support in memory data set cache.
Currently, Design-Time Data Cache is stored on disks. By performance tests using ramdisk, we found that caching in physical memory can improve the performance of RunAndRender by 30%.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/PreparedJointDataSourceQuery.java
/*******************************************************************************
 * Copyright (c) 2004, 2005 Actuate Corporation.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http:www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *  Actuate Corporation  - initial API and implementation
 *******************************************************************************/
package org.eclipse.birt.data.engine.impl;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import org.eclipse.birt.core.data.DataType;
import org.eclipse.birt.core.data.ExpressionUtil;
import org.eclipse.birt.core.exception.BirtException;
import org.eclipse.birt.data.engine.api.IBaseDataSetDesign;
import org.eclipse.birt.data.engine.api.IColumnDefinition;
import org.eclipse.birt.data.engine.api.IComputedColumn;
import org.eclipse.birt.data.engine.api.IJoinCondition;
import org.eclipse.birt.data.engine.api.IJointDataSetDesign;
import org.eclipse.birt.data.engine.api.IPreparedQuery;
import org.eclipse.birt.data.engine.api.IQueryDefinition;
import org.eclipse.birt.data.engine.api.IQueryResults;
import org.eclipse.birt.data.engine.api.IResultIterator;