Copyright © 2016 MariaDB. All rights reserved.
The ST_IsRing function was introduced in MariaDB 10.1.2
Returns true if a given LINESTRING is a ring, that is, both ST_IsClosed and ST_IsSimple. A simple curve does not pass through the same point more than once. However, see MDEV-7510.
St_IsRing() and IsRing() are synonyms.