Multi-bounding-box spatial index

Syntax

CREATE INDEX index_name ON table_name USING GIST(geom_column_name operator_class);

Parameters

Description

• For LineString and MultiLineString objects that contain many points or have a large spatial span, the object is split during index building to create a multi-bounding-box spatial index.

• The index split mode is specified by the ganos.geometry.mbbox_split_mode parameter. Valid values are length and points, which specify splitting by object length or by the number of points. The default value is length. The rules are as follows:

  • When you split by object length, the length of each segment is specified by the ganos.geometry.mbbox_split_length parameter. The maximum number of segments is specified by the ganos.geometry.mbbox_split_max_segments parameter. If splitting the object by the specified length results in more segments than the maximum allowed, the length of each segment is recalculated as: Total Length / Value of the `ganos.geometry.mbbox_split_max_segments` parameter.

  • When you split by the number of points, the number of points in each segment is specified by the ganos.geometry.mbbox_split_points parameter. The maximum number of segments is specified by the ganos.geometry.mbbox_split_max_segments parameter. If splitting by the specified number of points results in more segments than the maximum allowed, the number of points in each segment is recalculated as: Total Points / Value of the `ganos.geometry.mbbox_split_max_segments` parameter.

• Queries are transparent and require no changes to SQL statements.

Examples

• Geometry type

  CREATE TABLE line_test(id int, geom geometry);
  INSERT INTO line_test VALUES(1, st_geomfromtext('Linestring(0 1, 0 0, 1 0, 2 1,2 2,3 3)'));
  
  --- Create a 2D spatial index
  CREATE INDEX line_test_gist_geom_2d ON line_test USING GIST(geom);
  
  --- Create a 2D multi-bounding-box spatial index
  CREATE INDEX line_test_gist_geom_2dx ON line_test USING GIST(geom gist_geometry_ops_2dx);

• Geography type

  CREATE TABLE line_test(id int, geog geography);
  INSERT INTO line_test VALUES(1, st_geogfromtext('Linestring(0 1, 0 0, 1 0, 2 1,2 2,3 3)'));
  
  --- Create a 3D spatial index
  CREATE INDEX line_test_gist_geog_3d ON line_test USING GIST(geog);
  
  --- Create a 2D multi-bounding-box spatial index
  CREATE INDEX line_test_gist_geog_2dx ON line_test USING GIST(geog gist_geography_ops_2dx);