“Data Warehouses” are based on relational databases, and may include data management tools to extract data from various sources and manage that data. The data is transferred to the data warehouse in data packages that may include both data and metadata. Information related to the various data packages may be maintained in the data warehouse. All of the data and associated information is not necessarily held in the same database table. Rather, through the use of key fields, the data and associated information may be held in various tables that are linked together in an associated, relational database. The data warehouse operates in conjunction with, or “rides” on, the database.
Problems can arise when the links, that relate various data package information to each other, are broken. This can happen in a number of scenarios, some of which may not be avoidable, such as, for example, if a server shuts down at a particularly inappropriate moment. Often the reason for the link failure will not be known.
A link failure does not necessarily cause an immediate problem with operation of the data warehouse. However, if an operation on, or with, a data package (“a data request”) is attempted after a link failure, the data request will likely fail. One such data request involves an attempt to delete a data package. Since the links are broken, the system, in some operations, does not “see” the data package. This will cause the system to overlook the data package and not delete it from, for example, an entity that holds the data for reporting (“a data provider”).
Problems associated with such “invisible” data packages, which can not be “seen” by the data warehouse system because of link failures, are call “zombie” problems. One such zombie problem relates to requests involving such data. Such requests are called zombie requests. Zombie requests can cause major problems for the data provider because the request gets “locked” within the data warehouse or the data provider, is never fulfilled, and can not be deleted. However, most significantly, further data can not be loaded until the request is removed. Therefore this problem needs to be resolved with dispatch.
One way of addressing the problem of zombie requests is to have the database administrators remove all of the data and then reload the data. Another way of addressing the problem is to manually identify the data associated with the link failure. These techniques are labor intensive, time consuming, costly, and don't always succeed.