An update propagator for joint scalable storage

In recent years, the scalability of web applications has become crit- ical. Web sites get more dynamic and customized. This increases servers' workload. Furthermore, the future increase of load is dif- cult to predict. Thus, the industry seeks for solutions that scale well. With current technology, almost all items of system architec- tures can be multiplied when necessary. There are, however, prob- lems with databases in this respect. The traditional approach with a single relational database has become insu cient. In order to achieve scalability, architects add a number of di erent kinds of storage facil- ities. This could be error prone because of inconsistencies in stored data. In this paper, we present a novel method to assemble sys- tems with multiple storages. We propose an algorithm for update propagation among di erent storages like multi-column, key-value, and relational databases. We also apply this algorithm for consistent object caching, which reduces database workload and makes web ap- plication perform signi cantly better. Next, we describe PropScale, i.e. a proof-of-concept implementation of the proposed algorithm. Using this system we have conducted experimental evaluation of our solution. The results prove its robustness.