public Pair<Map<String, String>, Map<String, String>> readTagFile(long tagFileOffset)
      throws IOException {
    return tagLogFile.read(tagFileOffset);
  }
Rename the tag or attribute's key of the timeseries.

@param oldKey old key of tag or attribute
@param newKey new key of tag or attribute
@throws MetadataException tagLogFile write error or does not have tag/attribute or already has
    a tag/attribute named newKey
@throws IOException error occurred when reading disk
iotdb-core/datanode/src/main/java/org/apache/iotdb/db/schemaengine/schemaregion/tag/TagManager.java