There are benefits to using the sharding pattern, but a downside is that it can also increase the complexity of a project. Because of this, this pattern should only be used when necessary, as increasing the complexity of a project increases the chance of errors occurring. 

The sharding pattern should be used when the performance of retrieving data needs to be increased – in particular, when the data set is very large. The shards reduce the amount of data that is used to retrieve data, thereby increasing performance. Furthermore, using the sharding pattern makes it possible to scale the data store and also makes data highly available.