java/engine/org/apache/derby/impl/sql/compile/BaseJoinStrategy.java

/*

   Derby - Class org.apache.derby.impl.sql.compile.BaseJoinStrategy

   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.derby.impl.sql.compile;

import org.apache.derby.iapi.error.StandardException;
import org.apache.derby.iapi.reference.ClassName;
import org.apache.derby.iapi.services.compiler.MethodBuilder;
import org.apache.derby.iapi.sql.compile.ExpressionClassBuilderInterface;
import org.apache.derby.iapi.sql.compile.JoinStrategy;
import org.apache.derby.iapi.sql.compile.Optimizable;
import org.apache.derby.iapi.sql.compile.OptimizablePredicateList;
import org.apache.derby.iapi.sql.dictionary.ConglomerateDescriptor;
import org.apache.derby.iapi.sql.dictionary.ConstraintDescriptor;
import org.apache.derby.iapi.sql.dictionary.DataDictionary;
import org.apache.derby.iapi.sql.dictionary.TableDescriptor;
import org.apache.derby.iapi.store.access.StaticCompiledOpenConglomInfo;
import org.apache.derby.iapi.store.access.TransactionController;
import org.apache.derby.iapi.util.PropertyUtil;

abstract class BaseJoinStrategy implements JoinStrategy {
	BaseJoinStrategy() {
	}

	/** @see JoinStrategy#bulkFetchOK */
	public boolean bulkFetchOK() {
		return true;
	}

	/** @see JoinStrategy#ignoreBulkFetch */
	public boolean ignoreBulkFetch() {
		return false;
	}

	/**
	 * Push the first set of common arguments for obtaining a scan ResultSet from
	 * ResultSetFactory.
	 * The first 11 arguments are common for these ResultSet getters
	 * <UL>
	 * <LI> ResultSetFactory.getBulkTableScanResultSet
	 * <LI> ResultSetFactory.getHashScanResultSet
	 * <LI> ResultSetFactory.getTableScanResultSet
	 * <LI> ResultSetFactory.getRaDependentTableScanResultSet
	 * </UL>
	 * @param tc
	 * @param mb
	 * @param innerTable
	 * @param predList
	 * @param acbi
	 * @throws StandardException
	 */
	void fillInScanArgs1(
								TransactionController tc,
								MethodBuilder mb,
								Optimizable innerTable,
								OptimizablePredicateList predList,
								ExpressionClassBuilderInterface acbi,
								int resultRowTemplate
								)
					throws StandardException {
		boolean				   sameStartStopPosition = predList.sameStartStopPosition();
		ExpressionClassBuilder acb = (ExpressionClassBuilder) acbi;
		long				   conglomNumber = 
								innerTable.getTrulyTheBestAccessPath().
									getConglomerateDescriptor().
										getConglomerateNumber();
		StaticCompiledOpenConglomInfo scoci = tc.getStaticCompiledConglomInfo(conglomNumber);
		
		acb.pushThisAsActivation(mb);
		mb.push(conglomNumber);
		mb.push(acb.addItem(scoci));

        mb.push(resultRowTemplate);
		mb.push(innerTable.getResultSetNumber());

		predList.generateStartKey(acb, mb, innerTable);
		mb.push(predList.startOperator(innerTable));

		if (! sameStartStopPosition) {
			predList.generateStopKey(acb, mb, innerTable);
		} else {
			mb.pushNull(ClassName.GeneratedMethod);
		}

		mb.push(predList.stopOperator(innerTable));
		mb.push(sameStartStopPosition);

		predList.generateQualifiers(acb, mb, innerTable, true);
		mb.upCast(ClassName.Qualifier + "[][]");
	}

	final void fillInScanArgs2(MethodBuilder mb,
								Optimizable innerTable,
								int bulkFetch,
								int colRefItem,
								int indexColItem,
								int lockMode,
								boolean tableLocked,
								int isolationLevel) 
		throws StandardException
	{
		mb.push(innerTable.getBaseTableName());
		//User may have supplied optimizer overrides in the sql
		//Pass them onto execute phase so it can be shown in 
		//run time statistics.
		if (innerTable.getProperties() != null)
			mb.push(PropertyUtil.sortProperties(innerTable.getProperties()));
		else
			mb.pushNull("java.lang.String");

		ConglomerateDescriptor cd =
			innerTable.getTrulyTheBestAccessPath().getConglomerateDescriptor();
		if (cd.isConstraint())
		{
			DataDictionary dd = innerTable.getDataDictionary();
			TableDescriptor td = innerTable.getTableDescriptor();
			ConstraintDescriptor constraintDesc = dd.getConstraintDescriptor(
														td, cd.getUUID());
			mb.push(constraintDesc.getConstraintName());
		} else if (cd.isIndex())  {
			mb.push(cd.getConglomerateName());
		} else {
			mb.pushNull("java.lang.String");
		}

		// Whether or not the conglomerate is the backing index for a constraint
		mb.push(cd.isConstraint());

		// tell it whether it's to open for update, which we should do if
		// it's an update or delete statement, or if it's the target
		// table of an updatable cursor.
		mb.push(innerTable.forUpdate());

		mb.push(colRefItem);

		mb.push(indexColItem);

		mb.push(lockMode);

		mb.push(tableLocked);

		mb.push(isolationLevel);

		if (bulkFetch > 0) {
			mb.push(bulkFetch);
            // If the table references LOBs, we want to disable bulk fetching
            // when the cursor is holdable. Otherwise, a commit could close
            // LOBs before they have been returned to the user.
            mb.push(innerTable.hasLargeObjectColumns());
		}

		/* 1 row scans (avoiding 2nd next()) are
 		 * only meaningful for some join strategies.
		 * (Only an issue for outer table, which currently
		 * can only be nested loop, as avoidance of 2nd next
		 * on inner table already factored in to join node.)
		 */
		if (validForOutermostTable())
		{
			mb.push(innerTable.isOneRowScan());
		}

		mb.push(
				innerTable.getTrulyTheBestAccessPath().
												getCostEstimate().rowCount());

		mb.push(
						innerTable.getTrulyTheBestAccessPath().
										getCostEstimate().getEstimatedCost());
	}

	/**
	 * @see JoinStrategy#isHashJoin
	 */
	public boolean isHashJoin()
	{
		return false;
	}

	/**
	 * Can this join strategy be used on the
	 * outermost table of a join.
	 *
	 * @return Whether or not this join strategy
     * can be used on the outermost table of a join.
	 */
	protected boolean validForOutermostTable()
	{
		return false;
	}
}