A package index is a special kind of primary index. It maps the entire package to a single slot. It is used when further division of the package by a primary index is not warranted. A package index could be used to organize and make available a package of enduring reference articles on a current news site that uses a sliding timeline for all other articles.

When designing a search engine load, every package should be covered by a primary index or no package should be covered by a primary index. Unless the search engine load is very small, usually it is the former: every package should be covered by a primary index.

A package index is used to fulfill that requirement when, for some reason, it is not desirable to create a new primary index for mapping a package, or to include that package with other packages within an already defined primary index.

Package indexes are defined by the following properties: