User's Guide and Reference

Ways to create a spatial index

There are several ways to create a spatial index:

• Define one from the Create Spatial Index window. For instructions, see Creating spatial indexes.
• Invoke the db2gse.gse_enable_idx stored procedure in an application program. For information about this stored procedure, see Stored procedures.
• Issue the db2 create index command with the spatial_index function in the USING clause. For example:

  create index storesx1 on customers (loc) using spatial_index(10e0, 100e0, 1000e0)
   
  

The nature of spatial data requires that the database designer understand its relative size distribution. The designer must determine the optimum size and number of grid levels with which to create the spatial index.

The grid levels, <grid level 1>, <grid level 2>, and <grid level 3>, are entered by increasing the cell size. Thus, the second level must have a larger cell size than the first, and the third larger than the second. The first grid level is mandatory, but you can disable the second and third with a double precision zero value (0.0e0).