Binary Large Object (BLOB): A large object in a object oriented database is known as a BLOB. Data is stored in a BLOB is a sequence of bytes. Data which has to be stored in a BLOB can be anything from audio, video, text, document or any other multimedia content.
Disadvantages of BLOBs:
1) A BLOB has to be stored separately in different storage areas.
2) It is harder for the DBMS to hold contents of a BLOB in a memory buffer.
3) Processing overhead is high when transaction is logged for BLOB data.
4) To retrieve BLOB data from the database, special techniques are used.
Character Large Object (CLOB): A CLOB is used for storing 4 GB of single byte character data in the database. A CLOB contains only text.
NCLOB (National Character Large Object): It is an extension of CLOB and is used for storing multi byte character data. Here the characters are stored in a NLS (National Language Support) format.
BFILE: It is a data type for storing long binary file which is external to the database.