Spatial indexing

Spatial indexing is one of the most important concepts in Oracle Spatial. Using the index can dramatically reduce the query cost for many operations. As Oracle uses an R-tree index, there are actually no maintenance operations required once the index is built. However, there are several important considerations while building the index to get the best possible performance for queries. In the following section, we describe some of the most commonly used parameters in the Create Index statement.

Layer GTYPE for point data

As we mentioned in Chapter 1, Defining a Data Model for Spatial Data Storage, the LAYER_GTYPE parameter can be used to enforce type consistency across all the rows in the table. For point data, this parameter can also be used to improve the performance for spatial index-based queries against these tables. When an operator like SDO_RELATE is evaluated, the R-tree index is used to do the primary filtering. In some cases, the index nodes can be used to perform...