Many a time. Usually after observing that a database query that should have taken about 3 milliseconds took 3 seconds. Oh stupid me! I forgot to declare an index for that foreign key!
At your typical old-style deeds registry, they maintained a grantor/grantee index (card file transitioning to database at the time I last used a physical one, in the late eighties). So, if you were interested in a house owned by Billy Bob Jones, you went to that index and found the most recent conveyance under that name. It had a book and page number. Then you went into the stacks, pulled down the cited book and turned to the cited page. There you found the deed whereby Jimmy Earl Smith, et ux, sold the property to Mr. Jones. It had a reference to book and page with the deed that conveyed the property to Mr. Smith and his old lady. Etc.
Typically, there was a bank of coin-operated copiers in one corner of the records hall, into which you could pump nickels and dimes if you needed to copy any of the documents.
These days, you can do the paper chase online in many jurisdictions. The deeds registries contract out the work to a relatively small number of firms who scan and index all the documents and maintain a sub-website for the registry. Typically, you can search by owner or property location. You get back a list of documents. Then you can download tiffs of what you need (or are just nosy about). Some will also have aerial photographic maps of the lots and ground-level photos of the properties. With condos, you will often find floor-plans of the units.
I was not clear enough in my question. I did not mean an index as it relates to a database, but an index in the classic sense of a book index.
Have you ever created a human readable index?
An Index for a book is not a Concordance. A good index is more useful, but must be created with human intuition not by software alone. A good index often has cross-references and Double-Posting of synonymous terms.
What I was trying to describe was done to index items that had no real category system in place. It was created after the intuitive arrangement of the items in the catalog by paging through the printed copy and creating index entries from 30 years knowledge of the industry. Trade terms, slang terms and Vendor names where it made sense to use them.
Often catalogs have what looks like an index, but really is not an index. Computer software processes efficiently, but the output often is not that human readable.
For a long time my tag line was: “Bringing order to apparent chaos is the highest form of creativity.”