Simplify
SIMPLIFY(Geometry, float_tolerance)
Alias: ST_SIMPLIFY
Returns geometry simplified using specified tolerance. Simplifies a complex geometry, which is especially useful at lower zoom levels where a high number of vertices is not necessary.
Result type: geometry
Examples:
SELECT ASTEXT(SIMPLIFY(POLYFROMTEXT('POLYGON((0 0, 0 4, 4 6, 6 4, 8 2, 9 2, 10 2, 10 0, 0 0))'), 1));
POLYGON ((0 0, 0 4, 4 6, 8 2, 10 2, 10 0, 0 0))
SELECT ASTEXT(SIMPLIFY(POLYFROMTEXT('POLYGON((0 0, 0 4, 4 6, 6 4, 8 2, 9 2, 10 2, 10 0, 0 0))'), 5));
POLYGON ((0 0, 4 6, 10 2, 0 0))