今天有问题咨询了一下几个SDE For Oracle函数的效率比较问题：
问题如下： SDE提供了 ST_LineString、ST_Point、ST_PolyFromText几个函数来进行点，线，面的构建，同时也提供了 ST_Geometry函数进行点线面的构建，这些函数的功能都是相同的，到底谁的效率更好。
初步判断：
从字面上看ST_LINESTRING，ST_POINT应该是ST_GEOMETRY的子类，以我对ESRI研发人员的风格了解，应该不会每个函数使用不同的算法，这些对象应该最终都会指向同一个函数，也就是说效率是一样的，下面我们可以查看一下源码验证一下。
查看ST_LINESTRING是怎么定义的
SQL> select text from user_source where name='ST_LINESTRING' and type='TYPE BODY'; TEXT -------------------------------------------------------------------------------- Type Body st_linestring AS constructor Function st_linestring(geom_str clob,srid number) Return self AS result IS temp varchar2(1); tempraw raw(1); entity number; geom_type number; name varchar2(32); spref_r SDE.spx_util.spatial_ref_record_t; TEXT -------------------------------------------------------------------------------- shape SDE.st_geom_util.shape_r; is_empty boolean := False; rc number; buffer clob; Begin geom_type := SDE.st_geom_util.unspecified_type; buffer := geom_str; SDE.st_geom_util.get_type(buffer,entity,geom_type,is_empty,SDE.st_geom_util.l inestring_type); TEXT -------------------------------------------------------------------------------- If entity = SDE.st_geom_util.sg_illegal_shape THEN raise_application_error (SDE.st_type_util.st_geometry_invalid_type,'Invalid ST_Linestring type.'); End If; SDE.st_geom_util.get_name(entity,name); If name != 'LINESTRING' THEN TEXT -------------------------------------------------------------------------------- raise_application_error (SDE.st_type_util.st_geometry_invalid_type,'ST_Line string must use a LINESTRING type.'); End If; spref_r.srid := srid; rc := SDE.st_spref_util.select_spref(spref_r); If rc != SDE.st_type_user.se_success THEN raise_application_error (SDE.st_type_util.st_no_srid,'srid '||spref_r.srid|| TEXT -------------------------------------------------------------------------------- ' does not exist in st_spatial_references table.'); End If; shape.points := empty_blob(); shape.numpts := 0; shape.entity := 0; shape.minx := 0; shape.miny := 0; shape.maxx := 0; TEXT -------------------------------------------------------------------------------- shape.maxy := 0; shape.area := 0; shape.len := 0; shape.minz := NULL; shape.maxz := NULL; shape.minm := NULL; shape.maxm := NULL; temp := lpad('a', 1, 'a'); tempraw := utl_raw.cast_to_raw (temp); shape.points := tempraw; TEXT -------------------------------------------------------------------------------- If is_empty = False THEN SDE.st_geometry_shapelib_pkg.geometryfromtext(buffer,spref_r.srid,spref_r.x _offset,spref_r.y_offset,spref_r.xyunits, spref_r.z_offset,spref_r.z_sc ale,spref_r.m_offset,spref_r.m_scale, spref_r.Definit hape.minx,shape.miny, TEXT -------------------------------------------------------------------------------- shape.maxx,shap hape.maxm,shape.area,shape.len, shape.points); ELSE shape.numpts := 0; If geom_type > SDE.st_geom_util.unspecified_type Then shape.entity := geom_type; else shape.entity := 0; end if; TEXT -------------------------------------------------------------------------------- shape.minx := 0; shape.miny := 0; shape.maxx := 0; shape.maxy := 0; shape.minz := NULL; shape.maxz := NULL; shape.minm := NULL; shape.maxm := NULL; shape.area := 0; shape.len := 0; shape.points := empty_blob(); TEXT -------------------------------------------------------------------------------- shape.srid := srid; End If; if(shape.numpts IS NULL and shape.entity = 0) then self.entity := shape.entity; self.numpts := 0; self.minx := 0; self.maxx := 0; self.miny := 0; self.maxy := 0; self.minz := NULL; TEXT -------------------------------------------------------------------------------- self.maxz := NULL; self.minm := NULL; self.maxm := NULL; self.srid := srid; else self.entity := shape.entity; self.numpts := shape.numpts; self.minx := shape.minx; self.miny := shape.miny; self.maxx := shape.maxx; self.maxy := shape.maxy; TEXT -------------------------------------------------------------------------------- if(shape.minz IS NULL) then self.minz := NULL; else self.minz := shape.minz; end if; if(shape.maxz IS NULL) then self.maxz := NULL; else self.maxz := shape.maxz; TEXT -------------------------------------------------------------------------------- end if; if(shape.minm IS NULL) then self.minm := NULL; else self.minm := shape.minm; end if; if(shape.maxm IS NULL) then self.maxm := NULL; else TEXT -------------------------------------------------------------------------------- self.maxm := shape.maxm; end if; end if; self.area := 0; self.len := shape.len; self.srid := srid; self.points := shape.points; Return; End; TEXT -------------------------------------------------------------------------------- static Function get_release Return number IS c_type_release Constant pls_integer := 1007; Begin Return c_type_release; End get_release; End; SQL> select text from user_source where name='ST_GEOMFROMTEXT' and type='TYPE BODY'; TEXT -------------------------------------------------------------------------------- Type Body st_geomfromtext AS constructor Function st_geomfromtext(geom_str clob,srid number) Return self AS result IS temp varchar2(1); tempraw raw(1); entity number; geom_type number; name varchar2(32); spref_r SDE.spx_util.spatial_ref_record_t; TEXT -------------------------------------------------------------------------------- shape SDE.st_geom_util.shape_r; is_empty boolean := False; rc number; buffer clob; Begin geom_type := SDE.st_geom_util.unspecified_type; buffer := geom_str; SDE.st_geom_util.get_type(buffer,entity,geom_type,is_empty,SDE.st_geom_util.s t_geometry_type); TEXT -------------------------------------------------------------------------------- If entity = SDE.st_geom_util.sg_illegal_shape THEN raise_application_error (SDE.st_type_util.st_geometry_invalid_type,'Invalid ST_GEOMETRY type.'); End If; SDE.st_geom_util.get_name(entity,name); If name != 'POINT' AND name != 'LINESTRING' AND name != 'POLYGON' AND TEXT -------------------------------------------------------------------------------- name != 'MULTIPOINT' AND name != 'MULTILINESTRING' AND name != 'MULTIPOLYG ON' THEN raise_application_error (SDE.st_type_util.st_geometry_invalid_type,'ST_GEOM ETRY type must be a valid subtype.'); End If; spref_r.srid := srid; rc := SDE.st_spref_util.select_spref(spref_r); If rc <> SDE.st_type_user.se_success THEN TEXT -------------------------------------------------------------------------------- raise_application_error (SDE.st_type_util.spx_no_srid,'Parameter ST_SRID '|| spref_r.srid|| ' does not exist in ST_SPATIAL_REFERENCES table.'); End If; shape.points := empty_blob(); shape.numpts := 0; shape.entity := 0; TEXT -------------------------------------------------------------------------------- shape.minx := 0; shape.miny := 0; shape.maxx := 0; shape.maxy := 0; shape.area := 0; shape.len := 0; shape.minz := NULL; shape.maxz := NULL; shape.minm := NULL; shape.maxm := NULL; TEXT -------------------------------------------------------------------------------- -- Initialize POINTS blob. temp := lpad('a', 1, 'a'); tempraw := utl_raw.cast_to_raw (temp); shape.points := tempraw; If is_empty = False THEN SDE.st_geometry_shapelib_pkg.geometryfromtext (buffer,spref_r.srid,spref_r.x_ offset,spref_r.y_offset,spref_r.xyunits, spref_r.z_offset,spref_r.z_sca le,spref_r.m_offset,spref_r.m_scale, TEXT -------------------------------------------------------------------------------- spref_r.D ape.minx,shape.miny, shape.ma hape.maxm,shape.area,shape.len, shape.po ELSE shape.numpts := 0; TEXT -------------------------------------------------------------------------------- If geom_type > SDE.st_geom_util.unspecified_type Then shape.entity := geom_type; else shape.entity := 0; end if; shape.minx := 0; shape.miny := 0; shape.maxx := 0; shape.maxy := 0; shape.minz := NULL; shape.maxz := NULL; TEXT -------------------------------------------------------------------------------- shape.minm := NULL; shape.maxm := NULL; shape.area := 0; shape.len := 0; shape.points := empty_blob(); shape.srid := srid; End If; if(shape.numpts IS NULL and shape.entity = 0) then self.entity := shape.entity; self.numpts := 0; TEXT -------------------------------------------------------------------------------- self.minx := 0; self.maxx := 0; self.miny := 0; self.maxy := 0; self.minz := NULL; self.maxz := NULL; self.minm := NULL; self.maxm := NULL; self.srid := srid; else self.entity := shape.entity; TEXT -------------------------------------------------------------------------------- self.numpts := shape.numpts; self.minx := shape.minx; self.miny := shape.miny; self.maxx := shape.maxx; self.maxy := shape.maxy; if(shape.minz IS NULL) then self.minz := NULL; else self.minz := shape.minz; end if; TEXT -------------------------------------------------------------------------------- if(shape.maxz IS NULL) then self.maxz := NULL; else self.maxz := shape.maxz; end if; if(shape.minm IS NULL) then self.minm := NULL; else self.minm := shape.minm; TEXT -------------------------------------------------------------------------------- end if; if(shape.maxm IS NULL) then self.maxm := NULL; else self.maxm := shape.maxm; end if; end if; self.area := shape.area; TEXT -------------------------------------------------------------------------------- self.len := shape.len; self.srid := srid; self.points := shape.points; Return; End; static Function get_release Return number IS c_type_release Constant pls_integer := 1007; TEXT -------------------------------------------------------------------------------- Begin Return c_type_release; End get_release; End; CREATE OR REPLACE Type Body st_geometry AS constructor Function st_geometry (geom_str clob, srid number) Return self AS result IS temp varchar2(1); tempraw raw(1); entity number; geom_type number; name varchar2(32); spref_r SDE.st_spref_util.spatial_ref_record_t; shape SDE.st_geom_util.shape_r; is_empty boolean := False; rc number; buffer clob; Begin geom_type := SDE.st_geom_util.unspecified_type; buffer := geom_str; SDE.st_geom_util.get_type(buffer,entity,geom_type,is_empty,SDE.st_geom_util.st_geometry_type); If entity = SDE.st_geom_util.sg_illegal_shape THEN raise_application_error (SDE.st_type_util.st_geometry_invalid_type,'ST_GEOMETRY type must be a geometry type.'); End If; SDE.st_geom_util.get_name(entity,name); spref_r.srid := srid; rc := SDE.st_spref_util.select_spref(spref_r); If rc != SDE.st_type_user.se_success THEN raise_application_error (SDE.st_type_util.st_no_srid,'SRID '||spref_r.srid|| ' does not exist in ST_SPATIAL_REFERENCES table.'); End If; shape.points := empty_blob(); shape.numpts := 0; shape.entity := 0; shape.minx := 0; shape.miny := 0; shape.maxx := 0; shape.maxy := 0; shape.area := 0; shape.len := 0; shape.minz := NULL; shape.maxz := NULL; shape.minm := NULL; shape.maxm := NULL; temp := lpad('a', 1, 'a'); tempraw := utl_raw.cast_to_raw (temp); shape.points := tempraw; If is_empty = False THEN geom_type := SDE.st_geom_util.unspecified_type; SDE.st_geometry_shapelib_pkg.geometryfromtext(buffer,spref_r.srid,spref_r.x_offset,spref_r.y_offset,spref_r.xyunits, spref_r.z_offset,spref_r.z_scale,spref_r.m_offset,spref_r.m_scale, spref_r.Definition,geom_type,shape.numpts,shape.entity,shape.minx,shape.miny, shape.maxx,shape.maxy,shape.minz,shape.maxz,shape.minm,shape.maxm, shape.area,shape.len,shape.points);发现最终调用的是SDE.st_geometry_shapelib_pkg.geometryfromtext函数进行对象的构建。
所以效率是一样的。
