Major Description
Currently we use bitshuffle for all ints, including dictionary codewords. For dictionary codewords, we know the maximum possible value up-front, and we also know that the ints will be non-negative and small. This set of constraints makes it much better to use a specialized bitpacking algorithm rather than a more generic compression like bitshuffle+lz4. Based on some quick experiments I ran, we can probably get a several-fold decoding speedup with no loss of compression by switching to a codec like simdbitpacking for these codewords.