A keyset is a group of keys which share a common definition. A simple example is a telephone book. Each name is a key which points to a record containing that name's address and phone number and sometimes other items of information. In this example, the entire list of names is a keyset.
With HyperHIT, it is possible to create not only many keysets within a data file, but also subordinate keysets. Taking our phone book as an example, a subordinate keyset could be the departments and phone extension numbers for a department store whose main number is listed in the phone book.
When a keyset is accessed, it is cached in memory to optimize searches. You can use a keyset as a quick look-up table or to store mini records of less than 128 characters. For a very simple example, you could store all legal 2-letter state abbreviations in a keyset and check all user entries in a state field against the abbreviations for non-matching entries.
