Create a blob column
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 following example shows the use of a blob column and the bigintAsBlob function:
Create a table with a blob column:
CREATE TABLE IF NOT EXISTS cycling.lastname_bio (
lastname varchar PRIMARY KEY,
bio blob
);Insert data into the table:
INSERT INTO cycling.lastname_bio (
lastname, bio
) VALUES (
'TSATEVICH', bigintAsBlob(3)
);Query the table:
SELECT * FROM cycling.lastname_bio;Results
lastname | bio
-----------+--------------------
TSATEVICH | 0x0000000000000003
(1 rows)
lastname | bio
-----------+--------------------
TSATEVICH | 0x0000000000000003
(1 rows)The following example shows the use of blobAsBigint function.
Alter the table to add a bigint column:
ALTER TABLE cycling.lastname_bio
ADD id bigint;Insert additional data into the table:
INSERT INTO cycling.lastname_bio (
lastname, id
) VALUES (
'DUVAL', blobAsBigint(0x0000000000000003)
);Query the table:
SELECT * FROM cycling.lastname_bio;Results
SELECT * FROM cycling.lastname_bio;