Creating a blob column

Blob data type represents a constant hexadecimal number.

A blob (Binary Large OBject) data type represents a constant hexadecimal number defined as 0[xX](hex)+ where hex is a hexadecimal character, such as [0-9a-fA-F]. For example, 0xcafe. The maximum theoretical size for a blob is 2 GB. The practical limit on blob size, however, is less than 1 MB. A blob type is suitable for storing a small image or short string.

Blob conversion functions

These functions convert a native type into binary data (blob), and convert a blob back into a native type:

typeAsBlob(value)
blobAsType(value)

For every native non-blob data type supported by CQL, the typeAsBlob() function takes an argument of that data type and returns it as a blob.

Conversely, the blobAsType() function takes a 64-bit blob argument and converts it to a value of the specified data type, if possible.

The example below shows how to use bigintAsBlob:

CREATE TABLE bios ( 
   user_name varchar PRIMARY KEY, 
   bio blob
 );

INSERT INTO bios (user_name, bio) VALUES ('fred', bigintAsBlob(3));
 
SELECT * FROM bios;
 
 user_name | bio
-----------+--------------------
      fred | 0x0000000000000003

The example below shows how to use blobAsBigInt:

ALTER TABLE bios ADD id bigint;

INSERT INTO bios (user_name, id) VALUES ('fred', blobAsBigint(0x0000000000000003));

SELECT * FROM bios;

 user_name | bio                | id
-----------+--------------------+----
      fred | 0x0000000000000003 |  3