Modulo sharding is simple, but resizing the shard set can relocate many records. A key stored on shard key % oldShards must move when its destination under newShards has a different index.
Design a ModuloReshardingAnalyzer class:
ModuloReshardingAnalyzer() creates a stateless analyzer.int keysMoved(int[] keys, int oldShards, int newShards) returns the number of records whose shard index changes.
Each entry in keys represents one record. Duplicate keys therefore count separately. A record moves exactly when key % oldShards != key % newShards. Do not modify keys.
Example 1:
Input:
Output:
Explanation: Keys 0, 1, and 2 keep their shard indices. Keys 3 through 7 change destination, so five records move.
Example 2:
Input:
Output:
Explanation: Keys 10 and 30 move from shard 2 to shard 0. Keys 20 and 40 remain on shard 0.
Constraints
0 <= keys.length <= 10^50 <= keys[i] <= 10^91 <= oldShards, newShards <= 10^5- At most
100 calls are made to keysMoved.
Count Keys Moved by Reshardingmedium