A method and an apparatus that optimize operations for a key among a collection of key indexed data structures using meta data describing properties of the key with respect to the collection of data structures are described. The meta data may correspond to a cache dynamically updated to indicate invariants which are true for the key in a current state of the collection of data structures. Expensive calculations to search through the collection of data structures for the key may be avoided. For example, costly lookup operations over a collection of data structures may not be required at all if a key is known to always (or to never) reference certain specific values, or for these values to have certain meta-properties, in any of the collection of data structure globally throughout a system at a current state.