Database partitioning techniques to support reload in a main memory database system: MARS

The authors examine the effect of different partitioning techniques on the MMDB (main memory database) reload problem in terms of the number of I/Os for reload and number of MM references during transaction processing. The best technique is the one that yields the minimum overall cost with regard to both properties. It is shown that horizontal and single vertical partitioning are actually the only possible candidates. Physical vertical never yields the best result. In some very rare cases, group vertical outperforms the other techniques. If the database system encountered performs more selections than projections and joins, and more tuple modifications or tuple deletions than tuple insertions, then horizontal is the best technique. Otherwise, single vertical is the chosen technique. It is also shown that, if reload is the only concern, that is, if the transaction performance is not taken into account, then single vertical is always the best choice