Replace that page as soon as needed. FIFO or LRU replacement work. MRU is best. Use Yao to figure out how many pages you ll access at each level in k lookups. Queries of 1 and 2 tables.
Performance metric is query throughput.
Memory set big enough to hold about 8 concurrent working sets. Heuristic techniques are no good, though feedback-based admission control helps Later work on such admission control shows it's VERY tricky in mixed workloads.