Technologies are disclosed for mapping documents to candidate duplicate documents in a document corpus. A bitset optimized inverted index is created for a document corpus. A document is received for which candidate duplicate documents in the document corpus are to be identified. The document is tokenized using adaptive tokenization. A determination made as to whether tokens in the document are represented in the bitset optimized inverted index. A list of candidate duplicate documents is created for tokens represented in the optimized inverted index utilizing in-memory bitsets that map tokens to documents that contain the tokens in the document corpus.