profile

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Definition

Compatibility
Syntax
Command Fields
Behavior
Example
Enable Filtering
Unset a Filter

Definition

profile

Changed in version 5.0.

For a mongod instance, the command 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. If the profiler is disabled, the command configures how slow operations are logged to the diagnostic log.

On mongod, if the database profiler level is 2, full logging is enabled on the profiler and the diagnostic log.

At database profiler level 1, the following settings modify both the profiler and the diagnostic log:

If the database profiler level is 0, the database profiler is disabled. At level 0 the following settings only modify the diagnostic log:

For a mongos instance, the command only configures how operations get written to the diagnostic log. You cannot enable the database profiler on a mongos instance because mongos does not have any collections that the profiler can write to.

Starting in MongoDB 5.0, changes made to the database profiler level, slowms, sampleRate, or filter using the profile command or db.setProfilingLevel() wrapper method are recorded in the log file.

On mongos, you can set profile level to:

0 to set the slowms, sampleRate, and filter for the diagnostic log;
-1 to read the current settings.

The profiler is off by default.

Warning

Profiling can degrade performance and expose unencrypted query data in 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.

Compatibility

This command is available in deployments hosted in the following environments:

MongoDB Atlas: The fully managed service for MongoDB deployments in the cloud

Note

This command is supported in all MongoDB Atlas clusters. For information on Atlas support for all commands, see Unsupported Commands.

MongoDB Enterprise: The subscription-based, self-managed version of MongoDB
MongoDB Community: The source-available, free-to-use, and self-managed version of MongoDB

Syntax

The command has the following syntax:

db.runCommand(
  {
    profile: <level>,
    slowms: <threshold>,
    sampleRate: <rate>,
    filter: <filter expression>
  }
)

Command Fields

The command takes the following fields:

Field

Type

Description

profile

int

Configures the profiler level. The following profiler levels are available:

0

The profiler is off and does not collect any data. This is the default profiler level.

1

The profiler collects data for operations that take longer than the value of slowms or that match a filter.

When a filter is set:

The slowms and sampleRate options are not used for profiling.
The profiler only captures operations that match the filter.

2

The profiler collects data for all operations.

Since profiling is not available on mongos, the profile command cannot be used to set the profiling level to a value other than 0 on a mongos instance.

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.

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.

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

sampleRate

double

Optional. Default: 1.0

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

This argument affects the same setting as the configuration option operationProfiling.slowOpSampleRate and does not affect the slow oplog entry log messages on secondaries.

filter

object

Optional. A query that determines which operations are profiled or logged.

The filter query takes the following form:

{ <field1>: <expression1>, ... }

The query can be any legal find() operation where the query <field> matches a field in the profiler output.

This argument affects the same setting as the configuration option operationProfiling.filter. When filter is set, the slowms and sampleRate options are not used for profiling and slow-query log lines.

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.

When connected to a sharded cluster through mongos, you can run the profile command against any database.

Tip

Example

Enable Filtering

To enable profiling and filter the logged data:

db.runCommand(
   {
     profile: 1,
     filter:
        {
           $or:
           [
              { millis: { $gte: 100 } },
              { user: "testuser@admin" }
           ]
        }
   }
)

The filter only selects operations that are:

at least 100 milliseconds long, or
submitted by the testuser.

Unset a Filter

To clear a profile filter, run profile with the filter: "unset" option.

db.runCommand(
   {
      profile: 1,
      filter: "unset"
   }
)

The operation returns a document with the previous values for the settings.

To view the current profiling level, see db.getProfilingStatus().

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