Wal-Mart Stores Inc., which already has what many believe to be the biggest data warehouse in the retail industry, if not the biggest in the world, is expanding that system, according to Teradata, Wal-Mart's data-warehouse vendor.

Few details of the deal have been disclosed, but Teradata says that the expansion will allow Wal-Mart to enhance the applications that run on the system and deploy new apps designed to improve customer service.

Wal-Mart is believed to use a warehouse with hundreds of terabytes of data to study sales trends and track inventory and other tasks. The system is also the foundation for Wal-Mart's Retail Link decision-support system that Wal-Mart's suppliers use to study item-level inventory and sales information.

Teradata, a division of NCR Corp., also says that Discover Financial Services, a Morgan Stanley business unit, is building a multiterabyte data warehouse using its products for reporting and analysis applications. Discover has purchased Teradata hardware, software, and consulting services and will migrate data from a legacy warehouse to a Teradata-based system. The value of the contract was not disclosed.

Earlier this week, Teradata said it is releasing a beta version of Teradata 8, the next generation of its database and data-warehouse-management software.

The update has new event-detection and replication capabilities that improve its ability to operate in real time, and new features such as single sign-on and directory links that make it easier to integrate Teradata warehouses into enterprise IT systems. Teradata 8 is expected to ship by the end of the year.