Image Number 2 for United States Patent #6915305.
A database maintenance system and method are particularly suitable for maintaining a consistency of data between two or more database tables having schemas that may be heterogeneous (e.g., restructuring views of each other). Typically, one table is a base table and a second table is a restructuring view of the base table and may have been generated for faster query response, research, or the like. The restructuring view may have occurred naturally, or the base table may have been converted to the restructuring view using a series of operators and optionally, a middleware schema. The restructuring view maintenance system is preferably configured to monitor changes to the base table, including changes to data and to metadata. The maintenance system is configured to receive notification of a modification to a base table, investigate the modifications, and determine which operator(s) have been used to convert the base table to the restructuring view. For each modification to the base table, the system then determines, according to the type of modification and the type of transformation used, which of a selected group of actions to take to map the modification onto the restructuring view. The selected group of actions may include variously: insert, update, delete, rename relation, drop table, and rename column, according to the type of modification and the mapping of the relationship between the base table and the target table.
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