/*
* Copyright 2010 The Apache Software Foundation
*
* 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 maynot 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 applicablelaw 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.pig.util;
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.List;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hbase.util.Pair;
import org.apache.phoenix.compile.ColumnProjector;
import org.apache.phoenix.compile.QueryPlan;
import org.apache.phoenix.jdbc.PhoenixStatement;
import org.apache.phoenix.pig.PhoenixPigConfiguration;
import com.google.common.base.Function;
import com.google.common.base.Joiner;
import com.google.common.base.Preconditions;
import com.google.common.base.Throwables;
import com.google.common.collect.Lists;
/**
*
* A function to parse the select query passed to LOAD into a Pair of <table Name, List<columns>
*
*/
public class QuerySchemaParserFunction implements Function<String,Pair<String,String>> {
private static final Log LOG = LogFactory.getLog(QuerySchemaParserFunction.class);
private PhoenixPigConfiguration phoenixConfiguration;
public QuerySchemaParserFunction(PhoenixPigConfiguration phoenixConfiguration) {
Preconditions.checkNotNull(phoenixConfiguration);
this.phoenixConfiguration = phoenixConfiguration;
}
@Override
public Pair<String, String> apply(final String selectStatement) {
Preconditions.checkNotNull(selectStatement);
Preconditions.checkArgument(!selectStatement.isEmpty(), "Select Query is empty!!");
Preconditions.checkNotNull(this.phoenixConfiguration);
Connection connection = null;
try {
connection = this.phoenixConfiguration.getConnection();
final Statement statement = connection.createStatement();
final PhoenixStatement pstmt = statement.unwrap(PhoenixStatement.class);
final QueryPlan queryPlan = pstmt.compileQuery(selectStatement);
isValidStatement(queryPlan);
final String tableName = queryPlan.getTableRef().getTable().getName().getString();
final List<? extends ColumnProjector> projectedColumns = queryPlan.getProjector().getColumnProjectors();
final List<String> columns = Lists.transform(projectedColumns,
new Function<ColumnProjector,String>() {
@Override
public String apply(ColumnProjector column) {
return column.getName();
}
});
final String columnsAsStr = Joiner.on(",").join(columns);
return new Pair<String, String>(tableName, columnsAsStr);
} catch (SQLException e) {
LOG.error(String.format(" Error [%s] parsing SELECT query [%s] ",e.getMessage(),selectStatement));
Throwables.propagate(e);
} finally {
if(connection != null) {
try {
connection.close();
} catch(SQLException sqle) {
Throwables.propagate(sqle);
}
}
}
return null;
}
/**
* The method validates the statement passed to the query plan. List of conditions are
* <ol>
* <li>Is a SELECT statement</li>
* <li>doesn't contain ORDER BY expression</li>
* <li>doesn't contain LIMIT</li>
* <li>doesn't contain GROUP BY expression</li>
* <li>doesn't contain DISTINCT</li>
* <li>doesn't contain AGGREGATE functions</li>
* </ol>
* @param queryPlan
* @return
*/
private boolean isValidStatement(final QueryPlan queryPlan) {
if(queryPlan.getStatement().getOperation() != PhoenixStatement.Operation.QUERY) {
throw new IllegalArgumentException("Query passed isn't a SELECT statement");
}
if(!queryPlan.getOrderBy().getOrderByExpressions().isEmpty()
|| queryPlan.getLimit() != null
|| (queryPlan.getGroupBy() != null && !queryPlan.getGroupBy().isEmpty())
|| queryPlan.getStatement().isDistinct()
|| queryPlan.getStatement().isAggregate()) {
throw new IllegalArgumentException("SELECT statement shouldn't contain DISTINCT or ORDER BY or LIMIT or GROUP BY expressions");
}
return true;
}
}