What Is CLOB Data Type?


Larry Thompson

What Is CLOB Data Type?

The CLOB (Character Large Object) data type is used to store large amounts of character data in a database. It is typically used to store text documents, such as articles, blog posts, or even entire books. The CLOB data type is commonly supported by relational databases like Oracle, IBM DB2, and PostgreSQL.

Advantages of Using CLOB Data Type

There are several advantages to using the CLOB data type:

  • Flexibility: The CLOB data type allows you to store large amounts of text data, typically up to 4 gigabytes. This makes it suitable for storing lengthy documents without truncating or losing any information.
  • Efficient Retrieval: Retrieving and manipulating CLOB data is efficient because the database engine can perform operations on the entire document as a single entity.
  • Searchability: You can easily search and query the contents of a CLOB column using SQL queries or full-text search capabilities provided by the database engine.


The main difference between the CLOB and VARCHAR data types lies in their storage capacity. While VARCHAR has a maximum storage capacity of a few kilobytes (depending on the database), CLOB can handle much larger amounts of text.

If you try to store more text than the maximum limit of a VARCHAR column, it will either be truncated or result in an error. On the other hand, with a CLOB column, you don’t have to worry about such limitations.

Working with CLOB Data Type

To work with CLOB data, you can use various SQL commands and functions provided by the database. These commands allow you to:

  • Insert: Insert large amounts of text into a CLOB column using SQL INSERT statements.
  • Select: Retrieve and display the contents of a CLOB column using SELECT statements.
  • Update: Modify the content of a CLOB column using UPDATE statements.
  • Delete: Remove the entire content or part of it from a CLOB column using DELETE statements.

Additionally, you can use programming languages like Java or Python to interact with databases and manipulate CLOB data programmatically.


The CLOB data type is an essential feature in relational databases for storing and managing large amounts of character data. It provides flexibility, efficient retrieval, and searchability. When dealing with extensive text documents or other types of lengthy textual information, the CLOB data type proves to be invaluable.

Now that you understand what the CLOB data type is and its advantages, you can leverage it effectively in your database applications.

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