Dynamic programming solution for multiple query optimization problem

erved The “multiple query optimization” (MQO) prob lem has been studied in the database literature s 1980s. MQO tries to reduce the execution cost o group of queries by performing common tasks o once, whereas traditional query optimization cons ers a single query at a time. MQO has been formula in [6] as an NP-complete optimization problem whe several heuristic functions are used to direct an A∗ search. Later in [7], and [2] a more informed cost e mation function, which is more expensive to calcula has been used to reduce the number of states exp by theA∗ search. Recently research emphasis has b on efficiently generating alternative plans that ma mize shared operations [4,5]. Roy et al. [4] descr a greedy heuristic for genera ting promising alternative