MariaDB starting with 10.10.0
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The RANDOM_BYTES function generates a binary string of random bytes. It was
added in MariaDB 10.10.0.

Syntax
------

RANDOM_BYTES(length)

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

Given a length from 1 to 1024, generates a binary string of length consisting
of random bytes generated by the SSL library's random number generator.

See the RAND_bytes() function documentation of your SSL library for
information on the random number generator. In the case of OpenSSL, a
cryptographically secure pseudo random generator (CSPRNG) is used.

Statements containing the RANDOM_BYTES function are unsafe for statement-based
replication.

An error occurs if length is outside the range 1 to 1024.

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