The encoded-byte block will almost certainly be unusable as an indexed data-structure, although it depends on how clever you are encoding the block. Indexing the encoded-byte block will require an auxiliary array to translate from a word index to (at least) the starting index of the word in the encoded-byte block. With 100,000 or so words and a three-byte index per word, the auxiliary array costs 300,000 bytes.
This page last modified on 24 January 2006.