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Definition

profile

Enables, disables, or configures the Database Profiler. The profiler captures and records data on the performance of write operations, cursors, and database commands on a running mongod instance.

The profiler is off by default.

Important

Profiling can impact performance and shares settings with the system log. Carefully consider any performance and security implications before configuring and enabling the profiler on a production deployment.

See Profiler Overhead for more information on potential performance degradation.

The profile command has the following syntax:

{
  profile: <level>,
  slowms: <threshold>,
  sampleRate: <rate>
}
Field Type Description
profile int

Default: 0

Specifies which operations should be profiled.
The following profiler levels are available:
Level Description
-1 Returns the current profiler level, but does not change it.
0 Turns the profiler off so that it does not collect any data. This is the default profiler level.
1 Sets the profiler to collect data for operations that take longer than the value of slowms.
2 Sets the profiler to collect data for all operations.
slowms int

Optional. Default: 100

The slow operation time threshold, in milliseconds. Operations that run for longer than this threshold are considered slow.

When logLevel is set to 0, MongoDB records slow operations to the diagnostic log at a rate determined by slowOpSampleRate. For MongoDB 3.6 deployments, starting in version 3.6.11, the secondaries of replica sets log all oplog entry messages that take longer than the slow operation threshold to apply regardless of the sample rate.

At higher logLevel settings, all operations appear in the diagnostic log regardless of their latency with the following exception: the logging of slow oplog entry messages by the secondaries. The secondaries log only the slow oplog entries; increasing the logLevel does not log all oplog entries.

Note

This argument affects the same setting as the configuration option slowOpThresholdMs.

sampleRate double

Optional. Default: 1.0

The fraction of slow operations that should be profiled.
sampleRate accepts values between 0 and 1, inclusive.

Note

This argument affects the same setting as the configuration option slowOpSampleRate and does not affect the slow oplog entry log messages on secondaries (available starting in version 3.6.11 for MongoDB 3.6 deployments).

New in version 3.6.

The db.getProfilingStatus() and db.setProfilingLevel() shell methods provide wrappers around the profile command.

Behavior

The profile command obtains a write lock on the affected database while enabling or disabling the profiler. This is typically a short operation. The lock blocks other operations until the profile command has completed.

See also

Database Profiling.

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