Electronic commerce is emerging as a major application area for database systems. A large number of e-commerce stores provide electronic product catalogs that allow customers to search products of interest and store owners to manage various product information.

Due to the constant schema evolution and the sparsity of e-commerce data, most commercial e-commerce systems use the so-called vertical schema for data storage. However, query processing for data stored using vertical schema is extremely inefficient because current RDBMSs, especially its cost-based query optimizer, are specifically designed to deal with traditional horizontal schemas.

In this paper, we show that e-catalog management can be naturally supported in IBM?s System RX, the first DBMS that truly supports both XML and relational data in their native forms. By leveraging on System RX?s hybrid nature, we present a novel solution for storing, managing, and querying e-catalog data. In addition to traditional queries, we show that our solution supports semantic queries as well. Our solution does not require a separate query optimization layer, because query optimization is handled within the hybrid DBMS engine itself.