Have you ever created an index? I have. For 5-1/2 years I created and maintained a 3,000 page catalog for a wholesaler (37,000 items). The index entries were about 11,000 lines in a spreadsheet. (index entries, cross index entries, reverse naming index entries)
I extracted the final item sequencing from the print PDF so I could sort for reprinting the sections. Used PDFTK to open the .pdf, used an editor to remover the proportional spacing syntax where the numeral "1" was followed by the numeral "1". Then I used Grep to extract the numeric item numbers in sequence. Splashed that in a database with the new item description data and all I had to manually sort were the "new items". Then I would import the .txt file into Quark using Xdata. It worked great.
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.