public DBRecordReader(JDBCSplit split, DatabaseProperties dbProperties, DBManager dbManager) {
DatabaseType databaseType = null;
String sqlQuery = null;
try {
this.split = split;
databaseProperties = dbProperties;
connection = dbManager.getConnection();
connection.setAutoCommit(false);
statement =
connection.createStatement(ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY);
if (dbProperties.getConnectionUrl() != null) {
String databaseName = dbProperties.getConnectionUrl().split(":")[1];
databaseType = dbManager.getDatabaseType(databaseName);
} else {
databaseType = dbManager.getDatabaseName(connection);
}
sqlQuery =
new QueryConstructor().constructSelectQueryForReading(dbProperties, split, databaseType);
results = statement.executeQuery(sqlQuery);
} catch (ClassNotFoundException e) {
log.error("Failed to get connection", e);
} catch (SQLException e) {
log.error("Failed to fetch data from database using query: " + sqlQuery, e);
} catch (UnsupportedDatabaseException e) {
log.error("This database doesn't support by hive-jdbc-handler", e);
}
}
public boolean next(LongWritable key, MapWritable value) throws IOException {
try {
if (!results.next()) {
return false;
}
// Set the key field value as the output key value
key.set(pos + split.getStart());
ResultSetMetaData resultsMetaData = results.getMetaData();
int columnCount = resultsMetaData.getColumnCount();
List<String> names = new ArrayList<String>();
List<Integer> types = new ArrayList<Integer>();
// The column count starts from 1
for (int i = 1; i <= columnCount; i++) {
// This is the column name in db table
String name = resultsMetaData.getColumnName(i).toLowerCase();
// Get the relevant metaTable name
name = databaseProperties.getInputColumnMappingFields().get(name);
int type = resultsMetaData.getColumnType(i);
// Hive keeps column names in lowercase
names.add(name.toLowerCase());
types.add(type);
}
for (int j = 0; j < types.size(); j++) {
value.put(new Text(names.get(j)), getActualObjectTypeForValue(results, types, j));
}
pos++;
} catch (SQLException e) {
throw new IOException(e.getMessage());
}
return true;
}