private String getPartitionFilterString() {
    if (partitionFilterString == null) {
      Properties props = UDFContext.getUDFContext().getUDFProperties(
        this.getClass(), new String[]{signature});
      partitionFilterString = props.getProperty(PARTITION_FILTER);
    }
    return partitionFilterString;
  }
Get statistics about the data to be loaded. Only input data size is implemented at this time.
hcatalog/hcatalog-pig-adapter/src/main/java/org/apache/hive/hcatalog/pig/HCatLoader.java