1. Sharding(Shared Nothing), A way to achieve scale out. Its main purpose is to break through the I/O capability limitations of single node database servers and solve database scalability issues. Suitable for using data that is logically independent of the business, such as data from a single user on a blogger or Digger. Shard can be divided based on ID, time period, and table. If the result involves multiple shards, a database operation interface can be abstracted at the application layer to perform operations such as merge and sort on the results retrieved from multiple shards.