I did an append only list of URL's with RAW files where each bit says something is true/false about the url at that offset.

For example 26x26 RAW files asking if the page contains the letter combination "aa" or "ab" all the way up to "zy" and "zz".

When one types a search query after 2 letters a file is pulled, at the 3rd letter we have a second 2 letter combination. Then do the AND operation.

It is much like a bloom filter and tells you what is not in the set.