/**
* 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.hadoop.hive.jdbc;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;
import java.util.Properties;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hive.metastore.api.FieldSchema;
import org.apache.hadoop.hive.metastore.api.Schema;
import org.apache.hadoop.hive.serde.Constants;
import org.apache.hadoop.hive.serde2.SerDe;
import org.apache.hadoop.hive.serde2.lazy.LazySimpleSerDe;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorUtils;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorUtils.ObjectInspectorCopyOption;
import org.apache.hadoop.hive.serde2.objectinspector.StructField;
import org.apache.hadoop.hive.serde2.objectinspector.StructObjectInspector;
import org.apache.hadoop.hive.service.HiveInterface;
import org.apache.hadoop.hive.service.HiveServerException;
import org.apache.hadoop.io.BytesWritable;
/**
* HiveQueryResultSet.
*
*/
public class HiveQueryResultSet extends HiveBaseResultSet {
public static final Log LOG = LogFactory.getLog(HiveQueryResultSet.class);
private HiveInterface client;
private SerDe serde;
private int maxRows = 0;
private int rowsFetched = 0;
private int fetchSize = 50;
private List<String> fetchedRows;
private Iterator<String> fetchedRowsItr;
public HiveQueryResultSet(HiveInterface client, int maxRows) throws SQLException {
this.client = client;
this.maxRows = maxRows;
initSerde();
row = Arrays.asList(new Object[columnNames.size()]);
}
public HiveQueryResultSet(HiveInterface client) throws SQLException {
this(client, 0);
}
/**
* Instantiate the serde used to deserialize the result rows.
*/
private void initSerde() throws SQLException {
try {
Schema fullSchema = client.getSchema();
List<FieldSchema> schema = fullSchema.getFieldSchemas();
columnNames = new ArrayList<String>();
columnTypes = new ArrayList<String>();
StringBuilder namesSb = new StringBuilder();
StringBuilder typesSb = new StringBuilder();
if ((schema != null) && (!schema.isEmpty())) {
for (int pos = 0; pos < schema.size(); pos++) {
if (pos != 0) {
namesSb.append(",");
typesSb.append(",");
}
columnNames.add(schema.get(pos).getName());
columnTypes.add(schema.get(pos).getType());
namesSb.append(schema.get(pos).getName());
typesSb.append(schema.get(pos).getType());
}
}
String names = namesSb.toString();
String types = typesSb.toString();
serde = new LazySimpleSerDe();
Properties props = new Properties();
if (names.length() > 0) {
LOG.debug("Column names: " + names);
props.setProperty(Constants.LIST_COLUMNS, names);
}
if (types.length() > 0) {
LOG.debug("Column types: " + types);
props.setProperty(Constants.LIST_COLUMN_TYPES, types);
}
serde.initialize(new Configuration(), props);
} catch (Exception ex) {
ex.printStackTrace();
throw new SQLException("Could not create ResultSet: " + ex.getMessage(), ex);
}
}
@Override
public void close() throws SQLException {
client = null;
}
/**
* Moves the cursor down one row from its current position.
*
* @see java.sql.ResultSet#next()
* @throws SQLException
* if a database access error occurs.
*/
public boolean next() throws SQLException {
if (maxRows > 0 && rowsFetched >= maxRows) {
return false;
}
try {
if (fetchedRows == null || !fetchedRowsItr.hasNext()) {
fetchedRows = client.fetchN(fetchSize);
fetchedRowsItr = fetchedRows.iterator();
}
String rowStr = "";
if (fetchedRowsItr.hasNext()) {
rowStr = fetchedRowsItr.next();
} else {
return false;
}
rowsFetched++;
if (LOG.isDebugEnabled()) {
LOG.debug("Fetched row string: " + rowStr);
}
StructObjectInspector soi = (StructObjectInspector) serde.getObjectInspector();
List<? extends StructField> fieldRefs = soi.getAllStructFieldRefs();
Object data = serde.deserialize(new BytesWritable(rowStr.getBytes()));
assert row.size() == fieldRefs.size() : row.size() + ", " + fieldRefs.size();
for (int i = 0; i < fieldRefs.size(); i++) {
StructField fieldRef = fieldRefs.get(i);
ObjectInspector oi = fieldRef.getFieldObjectInspector();
Object obj = soi.getStructFieldData(data, fieldRef);
row.set(i, convertLazyToJava(obj, oi));
}
if (LOG.isDebugEnabled()) {
LOG.debug("Deserialized row: " + row);
}
} catch (HiveServerException e) {
if (e.getErrorCode() == 0) { // error code == 0 means reached the EOF
return false;
} else {
throw new SQLException("Error retrieving next row", e);
}
} catch (Exception ex) {
ex.printStackTrace();
throw new SQLException("Error retrieving next row", ex);
}
// NOTE: fetchOne dosn't throw new SQLException("Method not supported").
return true;
}
@Override
public void setFetchSize(int rows) throws SQLException {
fetchSize = rows;
}
@Override
public int getFetchSize() throws SQLException {
return fetchSize;
}
/**
* Convert a LazyObject to a standard Java object in compliance with JDBC 3.0 (see JDBC 3.0
* Specification, Table B-3: Mapping from JDBC Types to Java Object Types).
*
* This method is kept consistent with {@link HiveResultSetMetaData#hiveTypeToSqlType}.
*/
private static Object convertLazyToJava(Object o, ObjectInspector oi) {
Object obj = ObjectInspectorUtils.copyToStandardObject(o, oi, ObjectInspectorCopyOption.JAVA);
// for now, expose non-primitive as a string
// TODO: expose non-primitive as a structured object while maintaining JDBC compliance
if (obj != null && oi.getCategory() != ObjectInspector.Category.PRIMITIVE) {
obj = obj.toString();
}
return obj;
}
}