Syntax
------

UNCOMPRESS(string_to_uncompress)

Description
-----------

Uncompresses a string compressed by the COMPRESS() function. If the argument
is not a compressed value, the result is NULL. This function requires MariaDB
to have been compiled with a compression library such as zlib. Otherwise, the
return value is always NULL. The have_compress server system variable
indicates whether a compression library is present.

Examples
--------

SELECT UNCOMPRESS(COMPRESS('a string'));
+----------------------------------+
| UNCOMPRESS(COMPRESS('a string')) |
+----------------------------------+
| a string                         |
+----------------------------------+

SELECT UNCOMPRESS('a string');
+------------------------+
| UNCOMPRESS('a string') |
+------------------------+
| NULL                   |
+------------------------+

URL: https://mariadb.com/kb/en/uncompress/