Element Caches

When a user runs a prompted report containing an attribute element prompt or a hierarchy prompt, an element request is created. (Additional ways to create an element request are listed below.) An element request is actually a SQL statement that is submitted to the data warehouse. Once the element request is completed, the prompt can be resolved and sent back to the user. Element caching, set by default, allows for this element to be stored in memory so it can be retrieved rapidly for subsequent element requests without triggering new SQL statements against the data warehouse.

For example, if ten users run a report with a prompt to select a region from a list, when the first user runs the report, a SQL statement executes and retrieves the region elements from the data warehouse to store in an element cache. The next nine users see the list of elements return much faster than the first user because the results are retrieved from the element cache in memory. If element caching is not enabled, when the next nine users run the report, nine additional SQL statements will be submitted to the data warehouse, which puts unnecessary load on the data warehouse.

Element caches are the most-recently used lookup table elements that are stored in memory on the Intelligence Server or Developer machines so they can be retrieved more quickly. They are created when users:

Browse attribute elements in Developer using the Data Explorer, either in the Folder List or the Report Editor
Browse attribute elements in the Filter Editor
Execute a report containing a prompt exposing an attribute list (which includes hierarchies and element list types). The element list is displayed when the report executes and creates an element cache.

This section discusses the following topics concerning element caching: