1. A computer-implemented method for adding a new record to a hierarchical set of records having a plurality of hierarchical levels and a plurality of hierarchical depths, each of the records in the hierarchical set of records having a tag that is unique within the hierarchical set of records, the method comprising: identifying with a data storage system one of the records in the hierarchical set of records as the parent of the new record, wherein the identified record represents a message of an indented threaded discussion and identifying one or more records is performed in response to a user request to respond to the message; modifying the tag with the data storage system, thereby producing a key; adding the key to the new record with the data storage system; indexing a database storing the hierarchical set of records with the data storage system, thereby adding the new record to the hierarchical set of records, wherein indexing the database comprises applying the key to the hierarchical set of records in the database; and retrieving the added record from the database with the data storage system using the key which comprises a second tag uniquely identifying the added record, wherein each tag comprises a number including multiple digits indicating a depth and a level within the hierarchical set of records, wherein modifying the tag comprises selecting a digit and changing a value of the digit, thereby changing the level or the depth, or both, of said one of the records, and wherein applying the key to the hierarchical set of records in the database comprises selecting one or more records in the hierarchical set of the records having a tag that matches the key.