MongoDB Tip: The touch Command | MongoDB Blog` The touch command was introduced in MongoDB 2.2 and allows loading data from the data storage layer into memory, which can improve performance by preheating a newly started server or adding a new secondary to an existing replica set. The command is non-blocking on a mongod process, allowing it to be run concurrently with other commands. To invoke the touch command, you need to specify at least one of either "data: true" or "index: true", as both are off by default and will result in an error message if not included. When running the command, a replica set member will enter into a RECOVERING state to prevent reads from clients, but will return to normal operation once the operation completes.