Analyzing a Single Layer That Fills Only a Small Portion of the Extent

Assume that you have a layer that contains detailed street information for the city of San Francisco. This information is stored in a table called SF, in a column called GEOMETRY. The extents of this layer (in the USER_SDO_GEOM_METADATA view) are -90 to 90 and -180 to 180.

You start the Spatial Index Advisor. In the Add Layer dialog box, you select the layer SF(GEOMETRY). The layer alias is set to SF and the color is set to black. After you click OK, the application does the following:

You know that the data could take a while to draw. Because you are not yet ready to draw, you turn off (uncheck) Draw on zoom or pan. You know that the San Francisco data covers a very small portion of the layer, so you select Zoom > Extent, and in the dialog box you specify the bounding rectangle.

You decide to examine this geometries in detail and are now ready to draw, so you turn on (check) Draw on zoom or pan and click the Zoom to Reasonable Size toolbar button (or select View > Zoom to > Reasonable Size). You move the pointer to the center of the canvas and click.

You view the information and recommendations in the Tips area, and display fixed-size and variable-size tiles. Based on the information displayed, you determine that the index already has the proper tiling level and number of tiles.

You now want to try some queries on the data. You click the Query Rectangle toolbar button (or select Layer > Query > Rectangle), specify the rectangle in the dialog box, and click OK. You decide that the query performance is acceptable. You now want to try more queries. For each one, you click the horizontal scroll bar as needed to pan to the desired area, and query a desired geometry (Layer > Query > ...). In each case, you decide whether or not the query performance is acceptable.

See also: Usage scenarios, Main help topics (outline)