phoenix-core/src/main/java/org/apache/phoenix/compile/QueryPlan.java

/*
 * 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.phoenix.compile;

import java.sql.SQLException;
import java.util.List;

import org.apache.hadoop.hbase.client.ResultScanner;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.phoenix.compile.GroupByCompiler.GroupBy;
import org.apache.phoenix.compile.OrderByCompiler.OrderBy;
import org.apache.phoenix.execute.SortMergeJoinPlan;
import org.apache.phoenix.execute.visitor.QueryPlanVisitor;
import org.apache.phoenix.iterate.ParallelScanGrouper;
import org.apache.phoenix.iterate.ResultIterator;
import org.apache.phoenix.optimize.Cost;
import org.apache.phoenix.parse.FilterableStatement;
import org.apache.phoenix.parse.SelectStatement;
import org.apache.phoenix.query.KeyRange;
import org.apache.phoenix.schema.TableRef;



/**
 * 
 * Interface for an executable query plan
 *
 * 
 * @since 0.1
 */
public interface QueryPlan extends StatementPlan {
    /**
     * Get a result iterator to iterate over the results
     * @return result iterator for iterating over the results
     * @throws SQLException
     */
    public ResultIterator iterator() throws SQLException;
    
    public ResultIterator iterator(ParallelScanGrouper scanGrouper) throws SQLException;
    
    public ResultIterator iterator(ParallelScanGrouper scanGrouper, Scan scan) throws SQLException;

    public long getEstimatedSize();

    public Cost getCost();

    // TODO: change once joins are supported
    TableRef getTableRef();
    /**
     * Returns projector used to formulate resultSet row
     */
    RowProjector getProjector();
    
    Integer getLimit();

    Integer getOffset();

    /**
     * Return the compiled Order By clause of {@link SelectStatement}.
     */
    OrderBy getOrderBy();

    GroupBy getGroupBy();

    List<KeyRange> getSplits();

    List<List<Scan>> getScans();

    FilterableStatement getStatement();

    public boolean isDegenerate();
    
    public boolean isRowKeyOrdered();
    
    /**
     * 
     * @return whether underlying {@link ResultScanner} can be picked up in a round-robin 
     * fashion. Generally, selecting scanners in such a fashion is possible if rows don't
     * have to be returned back in a certain order.
     * @throws SQLException 
     */
    public boolean useRoundRobinIterator() throws SQLException;

    <T> T accept(QueryPlanVisitor<T> visitor);

    /**
     * <pre>
     * Get the actual OrderBys of this queryPlan, which may be different from {@link #getOrderBy()},
     * because {@link #getOrderBy()} is only the compiled result of {@link SelectStatement}.
     * The return type is List because we can get multiple OrderBys for the query result of {@link SortMergeJoinPlan},
     * eg. for the sql:
     * SELECT  * FROM T1 JOIN T2 ON T1.a = T2.a and T1.b = T2.b
     * The result of the sort-merge-join is sorted on (T1.a, T1.b) and (T2.a, T2.b) at the same time.
     * </pre>
     * @return
     */
    public List<OrderBy> getOutputOrderBys() ;
}