GetAppliedIndexKey returns key that used to store `applied log index` for `storage.DataStorage`.

GetHardStateKey returns key that used to store `raftpb.HardState`.

GetMaxIndexKey returns key that used to max applied log index.

GetMetadataKey returns key that used to store `shard metadata` for `storage.DataStorage`.

GetRaftLogKey returns key that used to store `raftpb.Entry`.

GetShardIDFromAppliedIndexKey returns shard id.

GetSnapshotKey returns the key used to store snapshot metadata in LogDB.

GetStoreIdentKey return key of StoreIdent.

DataPrefixSize data prefix size.

we use this fixed key to write a dummy record into the KVStore with sync=true to force a sync of the WAL of the KVStore.