/**
* Does the configuration setup and schema parsing and setup.
*
* @param table_schema String
* @param columnsToRead String
*/
private void setup(String table_schema) {
if (table_schema == null)
throw new RuntimeException(
"The table schema must be defined as colname type, colname type. All types are hive types");
// create basic configuration for hdfs and hive
conf = new Configuration();
hiveConf = new HiveConf(conf, SessionState.class);
// parse the table_schema string
List<String> types = HiveRCSchemaUtil.parseSchemaTypes(table_schema);
List<String> cols = HiveRCSchemaUtil.parseSchema(pcols, table_schema);
List<FieldSchema> fieldSchemaList = new ArrayList<FieldSchema>(cols.size());
for (int i = 0; i < cols.size(); i++) {
fieldSchemaList.add(
new FieldSchema(cols.get(i), HiveRCSchemaUtil.findPigDataType(types.get(i))));
}
pigSchema = new ResourceSchema(new Schema(fieldSchemaList));
props = new Properties();
// setting table schema properties for ColumnarSerDe
// these properties are never changed by the columns to read filter,
// because the columnar serde needs to now the
// complete format of each record.
props.setProperty(Constants.LIST_COLUMNS, HiveRCSchemaUtil.listToString(cols));
props.setProperty(Constants.LIST_COLUMN_TYPES, HiveRCSchemaUtil.listToString(types));
}
/**
* Only read the columns that were requested in the constructor.<br>
*
* @param struct ColumnarStruct
* @param path Path
* @return Tuple
* @throws IOException
*/
private Tuple readColumnarTuple(ColumnarStruct struct, Path path) throws IOException {
int[] columnIndexes = getRequiredColumns();
// the partition keys if any will already be in the UDFContext here.
String[] partitionKeys = getPartitionKeys(null, null);
// only if the path has changed should be run the
if (currentPath == null || !currentPath.equals(path)) {
currentPathPartitionKeyMap =
(partitionKeys == null)
? null
: pathPartitionerHelper.getPathPartitionKeyValues(path.toString());
currentPath = path;
}
// if the partitionColumns is null this value will stop the for loop
// below from trynig to add any partition columns
// that do not exist
int partitionColumnStartIndex = Integer.MAX_VALUE;
if (!(partitionColumns == null || partitionColumns.size() == 0)) {
// partition columns are always appended to the schema fields.
partitionColumnStartIndex = pigSchema.getFields().length;
}
// create tuple with determined previous size
Tuple t = tupleFactory.newTuple(columnIndexes.length);
// read in all columns
for (int i = 0; i < columnIndexes.length; i++) {
int columnIndex = columnIndexes[i];
if (columnIndex < partitionColumnStartIndex) {
Object obj = struct.getField(columnIndex);
Object pigType = HiveRCSchemaUtil.extractPigTypeFromHiveType(obj);
t.set(i, pigType);
} else {
// read the partition columns
// will only be executed if partitionColumns is not null
String key = partitionKeys[columnIndex - partitionColumnStartIndex];
Object value = currentPathPartitionKeyMap.get(key);
t.set(i, value);
}
}
return t;
}