Redis commands of keys and scan command

• Although by keys命令or scan命令you may find all the data having a Redis features, but they have some differences.

1. Command keys
   because Redis is single-threaded, when it needs to provide other services, keys command causes the server to block;

2. scan command
   scan command solves the problem caused by the command keys, but the scan command to get the data have duplicate may need to do a client deduplication.