In the telephone book, a search for the name Ann Jackson Smith would normally succeed, on the "Smith A" page.

Page 321		SMITH A
Smith A J	10 Main St Springvale	9257 5496

When the name being searched for is A J Smith or Ann Jackson Smith, the entry is found relatively easily by browsing through all of the Smith A J entries.

A search for A Smith or Ann Smith is slower because more names must be browsed. If the full name had been indexed, the search for Ann Smith would be faster and the search for Ann Jackson Smith even quicker.

Though this increases the size of each entry and the cost of capturing the information, the overall performance of searches is improved when there is more data in the name. Given a full name to search with, its entry can be found more quickly.

In addition, when the name being searched for has missing or extra words or words in a different order, the simple telephone book indexing system starts to break down.

Searches for Ann Jackson-Smith, Ann Smith Jackson or Smith Ann will fail unless the searcher, after failing on the "J" and "A" pages, permutes the words and looks on the "S" page.

Regardless, a search for Ann Jackson will never succeed if the entry in the book was Smith, J.A. or Smith, Ann Jackson.

If, however, the name Ann Jackson Smith was indexed on three pages of the telephone book, on an "Ann", "Jackson" and "Smith" page, by permuting the order of the words, then any of the above searches would succeed by opening one page.

Page 17		ANN Smith B
Ann, Smith Jackson	10 Main St Springvale	9257 5496

Page 119		JACKSON Ann K
Jackson, Ann Smith	10 Main St Springvale	9257 5496

Page 327		SMITH Alan
Smith Ann Jackson	10 Main St Springvale	9257 5496

The size of the telephone book increases, but search cost does not. The extra "index entries" increases the physical size, yet improves overall quality and performance because any search succeeds.

In computer databases, with today’s low data storage costs, regardless of the volume of the file, the right solution for name indexes is permutation of words in the index entries at update time. And storing multiple records on separate "pages" in the database just like our example in the telephone book above. Permutation of naming words at search time alone can not guarantee to overcome the missing word, extra word or gross single word errors. This is not a design problem that can be overcome with better design, it is a mathematical constraint.