COMPRESS

Compress a string. This function compresses a string argument and returns the result as a binary string, useful for saving storage space.

Syntax

COMPRESS(string_to_compress)

Description

Compresses a string and returns the result as a binary string. This function requires MariaDB to have been compiled with a compression library such as zlib. Otherwise, the return value is always NULL. The compressed string can be uncompressed with UNCOMPRESS().

The have_compress server system variable indicates whether a compression library is present.

Examples

SELECT LENGTH(COMPRESS(REPEAT('a',1000)));
+------------------------------------+
| LENGTH(COMPRESS(REPEAT('a',1000))) |
+------------------------------------+
|                                 21 |
+------------------------------------+

SELECT LENGTH(COMPRESS(''));
+----------------------+
| LENGTH(COMPRESS('')) |
+----------------------+
|                    0 |
+----------------------+

SELECT LENGTH(COMPRESS('a'));
+-----------------------+
| LENGTH(COMPRESS('a')) |
+-----------------------+
|                    13 |
+-----------------------+

SELECT LENGTH(COMPRESS(REPEAT('a',16)));
+----------------------------------+
| LENGTH(COMPRESS(REPEAT('a',16))) |
+----------------------------------+
|                               15 |
+----------------------------------+

See Also

• Automatic compression of columns

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