The IBM Informix Spatial DataBlade provides supports R-tree spatial indexes, which are used to query spatial columns that contain two-dimensional geographic data.
ArcGIS creates a spatial index when a feature class is first created by executing a CREATE INDEX SQL statement that includes a USING RTREE clause. The spatial index is created with the default parameter bottom_up_build = 'yes' and no index options.
CREATE INDEX <index> ON <table> (<spatial column> ST_Geometry_Ops) USING RTREE (bottom_up_build = 'yes');
The ST_Geometry_Ops is the Informix Spatial DataBlade operator class. ST_Geometry_Ops manages the R-tree index.
You do not need to tune the spatial index for performance, since this is all handled through the R-tree index. Therefore, you do not have to experiment with the spatial index by trying different cell sizes and different grid-level configurations.
R-tree index statistics
The Informix optimizer does not use the R-tree index unless the statistics on the table are up-to-date. If the R-tree index is created after the data has been loaded, the statistics are up-to-date, and the optimizer uses the index. However, if the index is created and data is loaded afterwards, the optimizer does not use the R-tree index because the statistics are out of date. To update the statistics, use the Analyze Datasets geoprocessing tool from ArcGIS, or the UPDATE STATISTICS Informix SQL statement from an SQL client.
UPDATE STATISTICS FOR TABLE <table_name>