The Google Architecture!!!
Google is designed to avoid disk seeks whenever possible, and this has had a
considerable influence on the design of the data structures. A lexicon in
memory is implemented in two parts: a list of words (concatenated together
but separated by nulls) and a hash table of pointers to doclists.

The Google search engine has two important features that help it produce
high precision results. First, it makes use of the link structure of the Web
to calculate a quality ranking for each web page. This ranking is called
PageRank.
The main goal of Google is to improve the quality of web search engines.

The PageRank of a page A is given as follows:
PR(A) = (1-d) + d (PR(T1)/C(T1) + ... + PR(Tn)/C(Tn))

We assume page A has pages T1...Tn which point to it . The parameter d is a
damping factor which can be set between 0 and 1. We usually set d to 0.85.
Also C(A) is defined as the number of links going out of page A.

The PageRank of a page A is given as follows:
PR(A) = (1-d) + d (PR(T1)/C(T1) + ... + PR(Tn)/C(Tn))

I am implement a variant form Google algoritm to support large document
indexing, but I don't understand well the source code form Firebird,
specific part about index, somebody can help me?
I am writing in C, accessing files form disk, indexing and serarching, on
future I will implement in Firebird.

Best regards,
Edmilson