Minimizing the Use of Catalog Functions

Compared to other ODBC functions, catalog functions are relatively slow. By caching information, applications can avoid multiple executions. Although it is almost impossible to write an ODBC application without catalog functions, their use should be minimized.

To return all result column information mandated by the ODBC specification, a driver may have to perform multiple queries, joins, subqueries, and unions to return the required result set for a single call to a catalog function. These particular elements of the SQL language are performance expensive.

Applications should cache information from catalog functions so that multiple executions are unnecessary. For example, call SQLGetTypeInfo once in the application and cache the elements of the result set that your application depends on. It is unlikely that any application uses all elements of the result set generated by a catalog function, so the cached information should not be difficult to maintain.