Many of experts in the computer community believe in that we are in the age of data explosion. A huge amount of data values is generated at each moment of time, that must be captured, gathered, stored, maintained, managed, processed, analyzed and probably visualized, to be beneficially applied; This is the major challenge of almost all current operational data-intensive applications in the real-world. In many of data-intensive applications, data are in form of data stream instead of stored data bases. Generally and most often, a single processor DSMS is not capable to process huge volume of input streams and cannot execute query operators continuously over them with satisfactory speed. To overcome this shortcoming, parallel execution of queries based on a multiprocessor platform is presented in this book to eliminate system bottleneck.