Performance analysis tools

Built-in diagnostic utilitiesBuilt-in diagnostic utilities

MongoDB offers utilities to help you get performance data:

• mongostat: Collects statistics on CPU and memory usage with MongoDB processes.
• mongotop: Collects data read/write statistics for each collection.

When calling these utilities, use the connection string with the username and password of the user with the mdbMonitor role, for example:

mongostat 5 --uri="mongodb://{<name_of_user_with_mdbMonitor_role>}:{<password>}@{<host>}:27018/?authSource=admin"
mongotop 5 --uri="mongodb://{<name_of_user_with_mdbMonitor_role>}:{<password>}@{<host>}:27018/?authSource=admin"

Here, both utilities provide a set of performance data with a polling interval of 5 seconds.

For more information about using monostat and mongotop, see the MongoDB documentation.

ProfilerProfiler

MongoDB has a built-in profiler. It collects query data and then uses it to determine a query optimization strategy. The profiler runs based on the MongoDB settings that you can set when creating a cluster or updating the DBMS settings:

• operationProfiling.mode;
• operationProfiling.slowOpThreshold.

To view the data collected by the profiler, use the system.profile collection in each database. Profiler collections are read-only to the user with the mdbMonitor role. By default, the data is duplicated in the logs.

For more information about configuring the profiler and how to interpret its results, see the MongoDB documentation.

Currently running queriesCurrently running queries

To view queries that do not pertain to the current user, run the db.currentOp() query under the user with the mdbMonitor role:

db.currentOp()

To view the current user's queries, run the db.currentOp() query with the true value to configure ownOps:

db.currentOp({ "$ownOps": true })

LogsLogs

You can find the most detailed information about MongoDB performance in the logs.