19. The computer program product of claim 18 , wherein the first store further comprises an indicator for indicating whether the statistics are valid.
19. The computer program product of claim 18 , wherein the first store further comprises an indicator for indicating whether the statistics are valid. 20. The computer program product of claim 19 , further causes the computer system to: upon storing the updated statistics in the second store, alter the indicator associated with corresponding statistics in the first store to indicate that the corresponding statistics are invalid.