28. The machine readable storage medium of claim 23 , further comprising instructions that when executed cause the system to perform at least one of: retrieving the query result for a query in the cache by its key; selecting a query and removing its result from the cache; and invalidating the query result for a query in the cache.
28. The machine readable storage medium of claim 23 , further comprising instructions that when executed cause the system to perform at least one of: retrieving the query result for a query in the cache by its key; selecting a query and removing its result from the cache; and invalidating the query result for a query in the cache. 30. The machine readable storage medium of claim 28 , further comprising instructions that when executed cause the system to: invalidate the query result for the query when a part of the result is invalid.