Spectrum Spatial strives to be as efficient as possible in evaluating an SQL query. It does this by delegating as much of the work to the data source provider as possible. Spectrum Spatial supports a number of data source providers natively, among them Oracle, TAB, SQL Server, PostGIS and GeoPackage, each of which supports its own set of operations. Spectrum Spatial works with the data source provider to come up with an execution plan that allows some or all aspects of the query to be delegated. Where the data source provider does not support the operation(s), processing is done in the middle tier by Spectrum Spatial.
This section explains the order of operations for query processing and the rules of delegation for each part of a query. Examples are provided that show what is delegated to the data source provider and what Spectrum Spatial must execute to satisfy the query.
Additionally, we have documented the support provided by each of our supported data source providers. We recommend you review the topic for your data source provider to learn what can be delegated. Then review the delegation rules and examples for how you can create high performing queries.