Query optimization based on time scheduling approach

Distributed database systems suffer from many difficulties. The most common difficulty is the environment where such systems mostly are running on unpredictable and volatile environments. So it is difficult to produce efficient database query optimization based on information available at compilation time. The performance of re-optimization techniques which are used by many systems suffers from problems. This paper attempts to reduce query re-optimization by executing a set of simple predefined queries in predefined time scheduling approach to collect estimates of statistics at runtime. For this purpose, a timer object with adaptive query processing systems is proposed. Experimental result is given to demonstrate the performance of real queries. This result shows significant performance improvements is obtained compared with other traditional approaches when the proposed object timer is used.