1. An information retrieval system comprising: a queue for storing load data requests; a set of two or more load servers for retrieving data from the queue and indexing documents for retrieval based on the data retrieved from the queue; first and second load monitors for monitoring operation of the load servers and providing new data on the queue accessible by the set of loaders, with the first load monitor configured to provide information regarding its operations to the second load monitor, and the second load monitor configured to respond to status information indicating failure of the first load monitor to take over monitoring of the load servers and providing new data on the queue; and wherein each load server is associated with a service-level-agreement data structure, the service-level-agreement data structure including a first field for identifying for which databases the load server is permitted to index documents; a second field for indicating a minimal priority of document indexing requests that the load server is permitted to accept; and a third field indicating a temporal aspect.