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## 10.4.3 Reference Documentation 

Config Database (page 737) Complete documentation of the content of the local database that MongoDB uses to store sharded cluster metadata. 

## Config Database 

The config database supports sharded cluster operation. See the Sharding (page 661) section of this manual for full documentation of sharded clusters. 

Important: Consider the schema of the config database internal and may change between releases of MongoDB. The config database is not a dependable API, and users should not write data to the config database in the course of normal operation or maintenance. 

Warning: Modification of the config database on a functioning system may lead to instability or inconsistent data sets. If you must modify the config database, use mongodump to create a full backup of the config database. 

To access the config database, connect to a mongos instance in a sharded cluster, and use the following helper: 

use config 

You can return a list of the collections, with the following helper: 

show collections 

