52. A computer-readable medium having stored thereon instructions, which, when executed by a processor in a document decompression system, causes the processor to perform a multi-tier document decompression method including the operations of: selecting a range of token positions in a set of documents, each token position in the range of token positions corresponding to a respective token in the set of documents; obtaining a set of first token identifiers from locations in a repository, the set of first token identifiers corresponding to the selected range of token positions in the set of documents, wherein the set of first token identifiers represent document content in the selected range of token positions in the set of documents; mapping each of the first token identifiers in the set of first token identifiers to a respective second token identifier, wherein each second token identifier uniquely represents a corresponding token in the set of documents, and each token comprises document content in the set of documents; mapping each respective second token identifier to a corresponding token in the set of documents; and reconstructing at least a portion of a document in the set of documents using the tokens from the mapping of the second token identifiers and using the token positions corresponding to the first token identifiers, wherein the mapping of each first token identifier is in accordance with a respective first lexicon for a portion of the set of documents, and the mapping of each second token identifier is in accordance with a second lexicon that maps second token identifiers to unique tokens in the set of documents.
52. A computer-readable medium having stored thereon instructions, which, when executed by a processor in a document decompression system, causes the processor to perform a multi-tier document decompression method including the operations of: selecting a range of token positions in a set of documents, each token position in the range of token positions corresponding to a respective token in the set of documents; obtaining a set of first token identifiers from locations in a repository, the set of first token identifiers corresponding to the selected range of token positions in the set of documents, wherein the set of first token identifiers represent document content in the selected range of token positions in the set of documents; mapping each of the first token identifiers in the set of first token identifiers to a respective second token identifier, wherein each second token identifier uniquely represents a corresponding token in the set of documents, and each token comprises document content in the set of documents; mapping each respective second token identifier to a corresponding token in the set of documents; and reconstructing at least a portion of a document in the set of documents using the tokens from the mapping of the second token identifiers and using the token positions corresponding to the first token identifiers, wherein the mapping of each first token identifier is in accordance with a respective first lexicon for a portion of the set of documents, and the mapping of each second token identifier is in accordance with a second lexicon that maps second token identifiers to unique tokens in the set of documents. 53. The computer-readable medium of claim 52 , wherein each second token identifier comprises an M bit integer value.