7. The system of claim 1 , wherein the operations further comprise: generating an execution tree based on a sequence of tokens, the execution tree including a plurality of nodes, a node of the execution tree being associated with one or more tokens; and associating the execution tree with a current version identifier of the token database.
7. The system of claim 1 , wherein the operations further comprise: generating an execution tree based on a sequence of tokens, the execution tree including a plurality of nodes, a node of the execution tree being associated with one or more tokens; and associating the execution tree with a current version identifier of the token database. 19. The system of claim 7 , wherein the operations further comprise executing one or more nodes of the execution tree associated with querying one or more tokens in the token database.