combining biword and positional indices

next word index

Record words that follow a given word.

A typical web query mixture was executed in 1/4 of the time of using just a positional index.

Required 26% more space over just having a positional index.

It is inefficient to merge positional postings lists for biwords which are queried often.

E.g. “Michael Jackson” / “Britney Spears”.