The definition of a database. It defines the structure and ... See subschema and XML schema. THIS DEFINITION IS FOR PERSONAL USE ONLY. All other reproduction requires permission.

Changes That Have No Effect on Existing View Descriptors The following changes to a SYSTEM 2000 database definition have no effect on existing view descriptors: creating or deleting indexes. inserting ...

But clearly, one of those reasons is the support for flexible schemas. In the RDBMS world, the schema—the definition of the tables and columns which make up a database—is relatively fixed.