A system has been developed permitting database
queries over data extracted from a CAD system where the
query result is returned back to the CAD for visualization
and analysis. This has several challenges. First, CAD
data representations use complex object-oriented schemas
and the query language must be object-oriented too.
Second, the query system resides outside the CAD system
and must therefore use standardized data exchange
formats for interoperability with the CAD. ISO STEP
standard exchange formats are used for the exchange.
Third, a CAD system cannot import an arbitrary object
structure but places restrictions on the imported objects to
be acceptable. Therefore, the query system must
complement the query results in order to produce an
acceptable CAD model, called the model completion of
the query. These problems have been solved using an
extensible object-relational query processor. The system
also supports queries combining CAD data with data from
other data sources.