Some ideas:
(1) A plan p_i can be labeled as redundant and removed if the cost under the best case (using the candidate indexes) is less than the cost under the worst case (using the candidate indexes) of some other plan p_j.
Note that if some slots of p_j require sorted order, then the worst case cost of p_j must be INF.
(2) Compute distance between plans,
(3) Sampling-based methods: (Need to think more carefully).
Some ideas: (1) A plan p_i can be labeled as redundant and removed if the cost under the best case (using the candidate indexes) is less than the cost under the worst case (using the candidate indexes) of some other plan p_j.
Note that if some slots of p_j require sorted order, then the worst case cost of p_j must be INF.
(2) Compute distance between plans,
(3) Sampling-based methods: (Need to think more carefully).