  In this paper, we present MorphStore, an open-source in-memory columnar
analytical query engine with a novel holistic compression-enabled processing
model. Basically, compression using lightweight integer compression algorithms
already plays an important role in existing in-memory column-store database
systems, but mainly for base data. In particular, during query processing,
these systems only keep the data compressed until an operator cannot process
the compressed data directly, whereupon the data is decompressed, but not
recompressed. Thus, the full potential of compression during query processing
is not exploited. To overcome that, we developed a novel compression-enabled
processing model as presented in this paper. As we are going to show, the
continuous usage of compression for all base data and all intermediates is very
beneficial to reduce the overall memory footprint as well as to improve the
query performance.
