When changes cannot be easily identified, a typical course of action is to compare a previous copy of the transaction system database with the current database. After the changes are identified, a copy of the current database is made for comparison in the next processing cycle. How much time should be allotted to the window in which transaction processing system databases are frozen can be a source of contention. Who has ongoing responsibility for data quality monitoring Data quality is not a one time concern to many firms that implement data warehouses. In a firm with complex feeder systems, it is not uncommon for previously undiscovered data quality problems occur after the big push to clean data for the initial load of the data warehouse is done.
Firms find it necessary to install procedures to regularly audit data quality.
And in most firms it is unclear who should have responsibility for executing these procedures. How are requests to make feeder transaction processing system changes approved and how is knowledge about the changes communicated Small changes in feeder transaction processing systems can have major impacts on the feed to a data warehouse. Conflicts arise when transaction processing system developers, under pressure from their users to make changes, now have to work with data warehouse developers to assess the impact on downstream systems. Even more vexing situations come when a change is made in the feeder transaction processing system and is not communicated to the data warehouse developers. IS to User issues User issues can be especially thorny with data warehouses because, unlike with transaction processing systems, use of data warehousing systems is often optional.