amplab/shark — pull request #280 by rxin (2014-02-19 19:59:25+00:00)
Title: Compression fixes

1. Fixed a bug that delta encoding was used for every column regardless of compression ratio.

2. Slightly improved performance of compression code. The AMPLab big data benchmark uservisits table used to take 3.5 mins on 5 nodes (20GB/node). With this tiny fix it takes slightly less than 3 mins.