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DQLMergeEngine.java
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/
DQLMergeEngine.java
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/*
* 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.shardingsphere.core.merge.dql;
import com.google.common.base.Function;
import com.google.common.collect.Lists;
import lombok.Getter;
import org.apache.shardingsphere.core.database.DatabaseTypes;
import org.apache.shardingsphere.core.execute.sql.execute.result.AggregationDistinctQueryResult;
import org.apache.shardingsphere.core.execute.sql.execute.result.DistinctQueryResult;
import org.apache.shardingsphere.core.execute.sql.execute.result.QueryResult;
import org.apache.shardingsphere.core.merge.MergeEngine;
import org.apache.shardingsphere.core.merge.MergedResult;
import org.apache.shardingsphere.core.merge.dql.groupby.GroupByMemoryMergedResult;
import org.apache.shardingsphere.core.merge.dql.groupby.GroupByStreamMergedResult;
import org.apache.shardingsphere.core.merge.dql.iterator.IteratorStreamMergedResult;
import org.apache.shardingsphere.core.merge.dql.orderby.OrderByStreamMergedResult;
import org.apache.shardingsphere.core.merge.dql.pagination.LimitDecoratorMergedResult;
import org.apache.shardingsphere.core.merge.dql.pagination.RowNumberDecoratorMergedResult;
import org.apache.shardingsphere.core.merge.dql.pagination.TopAndRowNumberDecoratorMergedResult;
import org.apache.shardingsphere.core.optimize.statement.sharding.dml.select.pagination.Pagination;
import org.apache.shardingsphere.core.optimize.statement.sharding.dml.select.ShardingSelectOptimizedStatement;
import org.apache.shardingsphere.core.parse.sql.context.selectitem.AggregationDistinctSelectItem;
import org.apache.shardingsphere.core.parse.util.SQLUtil;
import org.apache.shardingsphere.core.route.SQLRouteResult;
import org.apache.shardingsphere.spi.database.DatabaseType;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;
/**
* DQL result set merge engine.
*
* @author zhangliang
* @author panjuan
*/
public final class DQLMergeEngine implements MergeEngine {
private final DatabaseType databaseType;
private final SQLRouteResult routeResult;
private final ShardingSelectOptimizedStatement optimizedStatement;
private final List<QueryResult> queryResults;
@Getter
private final Map<String, Integer> columnLabelIndexMap;
public DQLMergeEngine(final DatabaseType databaseType, final SQLRouteResult routeResult, final List<QueryResult> queryResults) throws SQLException {
this.databaseType = databaseType;
this.routeResult = routeResult;
this.optimizedStatement = (ShardingSelectOptimizedStatement) routeResult.getOptimizedStatement();
this.queryResults = getRealQueryResults(queryResults);
columnLabelIndexMap = getColumnLabelIndexMap(this.queryResults.get(0));
}
private List<QueryResult> getRealQueryResults(final List<QueryResult> queryResults) {
List<QueryResult> result = queryResults;
if (1 == result.size()) {
return result;
}
List<AggregationDistinctSelectItem> aggregationDistinctSelectItems = optimizedStatement.getAggregationDistinctSelectItems();
if (!aggregationDistinctSelectItems.isEmpty()) {
result = getDividedQueryResults(new AggregationDistinctQueryResult(queryResults, aggregationDistinctSelectItems));
}
if (isNeedProcessDistinctSelectItem()) {
result = getDividedQueryResults(new DistinctQueryResult(queryResults, new ArrayList<>(optimizedStatement.getDistinctSelectItem().get().getDistinctColumnLabels())));
}
return result.isEmpty() ? queryResults : result;
}
private List<QueryResult> getDividedQueryResults(final DistinctQueryResult distinctQueryResult) {
return Lists.transform(distinctQueryResult.divide(), new Function<DistinctQueryResult, QueryResult>() {
@Override
public QueryResult apply(final DistinctQueryResult input) {
return input;
}
});
}
private boolean isNeedProcessDistinctSelectItem() {
return optimizedStatement.getDistinctSelectItem().isPresent() && optimizedStatement.getGroupBy().getItems().isEmpty();
}
private Map<String, Integer> getColumnLabelIndexMap(final QueryResult queryResult) throws SQLException {
Map<String, Integer> result = new TreeMap<>(String.CASE_INSENSITIVE_ORDER);
for (int i = queryResult.getColumnCount(); i > 0; i--) {
result.put(SQLUtil.getExactlyValue(queryResult.getColumnLabel(i)), i);
}
return result;
}
@Override
public MergedResult merge() throws SQLException {
if (1 == queryResults.size()) {
return new IteratorStreamMergedResult(queryResults);
}
optimizedStatement.setIndexForItems(columnLabelIndexMap);
return decorate(build());
}
private MergedResult build() throws SQLException {
if (!optimizedStatement.getGroupBy().getItems().isEmpty() || !optimizedStatement.getAggregationSelectItems().isEmpty()) {
return getGroupByMergedResult();
}
if (!optimizedStatement.getOrderBy().getItems().isEmpty()) {
return new OrderByStreamMergedResult(queryResults, optimizedStatement.getOrderBy().getItems());
}
return new IteratorStreamMergedResult(queryResults);
}
private MergedResult getGroupByMergedResult() throws SQLException {
return optimizedStatement.isSameGroupByAndOrderByItems()
? new GroupByStreamMergedResult(columnLabelIndexMap, queryResults, optimizedStatement) : new GroupByMemoryMergedResult(columnLabelIndexMap, queryResults, optimizedStatement);
}
private MergedResult decorate(final MergedResult mergedResult) throws SQLException {
Pagination pagination = ((ShardingSelectOptimizedStatement) routeResult.getOptimizedStatement()).getPagination();
if (!pagination.isHasPagination() || 1 == queryResults.size()) {
return mergedResult;
}
String trunkDatabaseName = DatabaseTypes.getTrunkDatabaseType(databaseType.getName()).getName();
if ("MySQL".equals(trunkDatabaseName) || "PostgreSQL".equals(trunkDatabaseName)) {
return new LimitDecoratorMergedResult(mergedResult, pagination);
}
if ("Oracle".equals(trunkDatabaseName)) {
return new RowNumberDecoratorMergedResult(mergedResult, pagination);
}
if ("SQLServer".equals(trunkDatabaseName)) {
return new TopAndRowNumberDecoratorMergedResult(mergedResult, pagination);
}
return mergedResult;
}
}