CLOB stands for Character Large Object. A CLOB is a type of data that is used by different database management systems. It stores large amounts of data about characters, up to 4 GB in size. The CLOB data type is similar to a BLOB but includes character encoding which defines a set of characters and the representation of each character. In contrast, BLOB data is composed of unformatted binary data.

Common types of data used to store character data are char, varchar, and text. Certain database management systems also support additional types of text data such as small text, medium text, and long text. The CLOB data type may be used if the standard character data types are not large enough for a given database field. Because CLOB data can be very large, some database management systems do not directly store the text in the table. The CLOB field instead serves as an address, which refers to the location of the data.

How do CLOBs work?

Character Large Objects encompass all database objects with strings like all objects which contain character files. Character strings are letter sequences, digits, special characters, and control characters; therefore, CLOB entries typically reference text documents. What’s special about storing these large types of data is that with few exceptions, they are not contained directly in the database but a separate location. The database itself contains only a mechanism of reference pointing towards the respective CLOB. A website’s entire character code is not stored in a database cell but instead a reference number that links to the actual storage location of the HTML document underlying it.

Pros and Cons of CLOB storage

One of the major advantages of data type CLOB is the ability to read and edit individual files. CLOBs store the documents in full with text or characters, and its content can be examined in detail. Administrators can determine exactly if the content is duplicated or if parts of the text overlap.

Saving letters, digits, special characters, and control characters as CLOBs is loss-free when saving files often depends on whether all the document information needs to be saved which is not a problem with this data format. As a CLOB, you can also save a document’s meta-information along with the actual content. Therefore, most databases even support the presentation of Character Large Objects in a tree structure and the navigation and search for specific content.

The disadvantages of this type of data for storing huge numbers of characters include the fact that certain databases do not allow editing with familiar SQL functions. CLOBs store extremely large quantities of text, meaning it would take a very long time to execute the standard functions. Another disadvantage of CLOBs is that relatively small data elements are reserved outside the database and waste valuable storage space since defined, segmented storage space.