108

I have been pretty much fascinated by these two data types. According to Oracle Docs, they are presented as follows :

BLOB : Variable-length binary large object string that can be up to 2GB (2,147,483,647) long. Primarily intended to hold non-traditional data, such as voice or mixed media. BLOB strings are not associated with a character set, as with FOR BIT DATA strings.

CLOB : Variable-length character large object string that can be up to 2GB (2,147,483,647) long. A CLOB can store single-byte character strings or multibyte, character-based data. A CLOB is considered a character string.

What I don't know, is whether there is any difference between the two from DB2 and Oracle perspective? I mean, what are the differences between DB2 CLOB and Oracle CLOB, also between DB2 BLOB and Oracle BLOB? What is the maximum size of both in DB2 and Oracle? Is it just 2 GB ?

Hash
  • 4,517
  • 5
  • 19
  • 36
The Dark Knight
  • 4,986
  • 10
  • 42
  • 86

3 Answers3

123

BLOB is for binary data (videos, images, documents, other)

CLOB is for large text data (text)

Maximum size on MySQL 2GB

Maximum size on Oracle 128TB

scientific
  • 1,239
  • 2
  • 6
  • 2
67

BLOB primarily intended to hold non-traditional data, such as images,videos,voice or mixed media. CLOB intended to retain character-based data.

Pavel
  • 4,222
  • 7
  • 42
  • 67
Dnyaneshwar
  • 679
  • 5
  • 2
  • 4
    The difference is apparent when you have to re-encode or transmit them. Binary objects should not be translated in transport. Character objects can contain mixed-width characters. Binary objects are possibly non-printable. All character is binary, the converse is not necessarily true once you leave the database, nor again when leaving the platform. – mckenzm Apr 21 '16 at 05:18
45

They can be considered as equivalent. The limits in size are the same:

  • Maximum length of CLOB (in bytes or OCTETS)) 2 147 483 647
  • Maximum length of BLOB (in bytes) 2 147 483 647

There is also the DBCLOBs, for double byte characters.

References:

AngocA
  • 7,352
  • 4
  • 34
  • 51
  • 10
    "They can be considered as equivalent" _in size_. The behaviour on different types of contained data may be very different and should probably have been included in your answer. The hint is in the first letter of the acronym. – underscore_d Sep 09 '15 at 09:52