Number of bytes = (15+L)*U + U*PAGESIZE * R + T
where:
L = average term length for
the vocabulary
U = number of unique terms in the vocabulary
R = number of millions of documents
T = total number of all terms in all documents
The temporary space required in bytes for the TEXT index
is (M+20)* T, where:
Note: The temporary space required is subject to compressibility
of the sort data.