MySQL 8.0 Release Notes
MySQL 8.0 Source Code Documentation
A GeomCollection is a geometry that is a
collection of zero or more geometries of any class.
GeomCollection and
GeometryCollection are synonymous, with
GeomCollection the preferred type name.
All the elements in a geometry collection must be in the same
spatial reference system (that is, in the same coordinate
system). There are no other constraints on the elements of a
geometry collection, although the subclasses of
GeomCollection described in the following
sections may restrict membership. Restrictions may be based
on:
Element type (for example, a
MultiPointmay contain onlyPointelements)Dimension
Constraints on the degree of spatial overlap between elements