Structuring data for efficient I/O 4 format compre addr. Row vs column storage Definition Row storage respects internal structure of the data and puts the different items one next in a sequence Column storage breaks the internal structure of the data to collate similar pieces Why to use column o to optimize I/O in general and avoid scattered reads o to optimize data compression o to optimize parallelization of processing Drawback of column storage o a column organized file cannot be updated easily o column storage is usually created from row storage in a postprocessing phase. 10Structuring data for efficient I/O 10 / 42 S. Ponce - CERN format compress addr state c/c row/col Row vs column storage Definition Row storage respects internal structure of the data and puts the different items one next in a sequence Column storage breaks the internal structure of the data to collate similar pieces Why to use column ? to optimize I/O in general and avoid scattered reads to optimize data compression to optimize parallelization of processing Drawback of column storage a column organized file cannot be updated easily column storage is usually created from row storage in a postprocessing phase