mysql> SET @pt = ST_GeomFromText(’POINT(0 0)’); mysql> SET @pt_strategy = ST_Buffer_Strategy(’point_square’); mysql> SELECT ST_AsText(ST_Buffer(@pt, 2, @pt_strategy)); +--------------------------------------------+ | ST_AsText(ST_Buffer(@pt, 2, @pt_strategy)) | +--------------------------------------------+ | POLYGON((-2 -2,2 -2,2 2,-2 2,-2 -2)) | +--------------------------------------------+ 

mysql> SET @ls = ST_GeomFromText(’LINESTRING(0 0,0 5,5 5)’); mysql> SET @end_strategy = ST_Buffer_Strategy(’end_flat’); mysql> SET @join_strategy = ST_Buffer_Strategy(’join_round’, 10); mysql> SELECT ST_AsText(ST_Buffer(@ls, 5, @end_strategy, @join_strategy)) +---------------------------------------------------------------+ | ST_AsText(ST_Buffer(@ls, 5, @end_strategy, @join_strategy)) | +---------------------------------------------------------------+ | POLYGON((5 5,5 10,0 10,-3.5355339059327373 8.535533905932738, | | -5 5,-5 0,0 0,5 0,5 5)) | +---------------------------------------------------------------+ 

• ST_Buffer_Strategy( strategy  [, points_per_circle ]) 

This function returns a strategy byte string for use with ST_Buffer()  to influence buffer computation. 

Information about strategies is available at Boost.org. 

The first argument must be a string indicating a strategy option: 

•For point strategies, permitted values are ’point_circle’  and ’point_square’ . 

•For join strategies, permitted values are ’join_round’  and ’join_miter’ . 

•For end strategies, permitted values are ’end_round’  and ’end_flat’ . 

If the first argument is ’point_circle’ , ’join_round’ , ’join_miter’ , or ’end_round’ , the points_per_circle  argument must be given as a positive numeric value. The maximum points_per_circle  value is the value of the max_points_in_geometry  system variable. 

For examples, see the description of ST_Buffer() . 

ST_Buffer_Strategy()  handles its arguments as described in the introduction to this section, with these exceptions: 

•If any argument is invalid, an ER_WRONG_ARGUMENTS  error occurs. 

•If the first argument is ’point_square’  or ’end_flat’ , the points_per_circle  argument must not be given or an ER_WRONG_ARGUMENTS  error occurs. 

• ST_ConvexHull( g ) 

Returns a geometry that represents the convex hull of the geometry value g . 

This function computes a geometry’s convex hull by first checking whether its vertex points are colinear. The function returns a linear hull if so, a polygon hull otherwise. This function processes geometry 

