Lawrence Berkeley National Laboratory

Bulk of the streaming data from scientific simulations and experiments consists of numerical values, and these values often change in unpredictable ways over a short time horizon. Such data values are known to be hard to compress, however, much of the random fluctuation is not essential to the scientific application and could therefore be removed without adverse impact. We have developed a compression technique based on statistical similarity that could reduce the storage requirement by over 100-fold while preserve prominent features in the data stream. We achieve these impressive compression ratios because most data blocks have similar probability distribution and could be reproduced from a small block. The core concept behind this work is the exchangeability in statistics. To create a practical compression algorithm, we choose to work with fixed size blocks and use Kolmogorov-Smirnov test to measure similarity. The resulting technique could be regarded as a dictionary-based compression scheme. In this paper, we describe the method and explore its effectiveness on two sets of application data. We pay particular attention to the Fourier components of the reconstructed data and show that in addition to preserving unique features in data it is also faithfully preserving the Fourier components whose periods extend more than a few blocks.