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setFeatureCompatibilityVersion

setFeatureCompatibilityVersion

Enables or disables the features that persist data incompatible with earlier versions of MongoDB. You can only issue the setFeatureCompatibilityVersion against the admin database.

The command takes the following form:

db.adminCommand( { setFeatureCompatibilityVersion: <version> } )

The values for the version are:

Version
Description
"4.4"

Available on MongoDB 4.4 Deployments

Enables the 4.4 features that persist data incompatible with MongoDB 4.2.

Enabling these backwards-incompatible features can complicate the downgrade process since you must remove any persisted backwards-incompatible features before you downgrade.

It is recommended that after upgrading, you allow your deployment to run without enabling these features for a burn-in period to ensure the likelihood of downgrade is minimal. When you are confident that the likelihood of downgrade is minimal, enable these features.

"4.2"

Available on MongoDB 4.2 and 4.4 Deployments

Enables the 4.2 features that persist data incompatible with MongoDB 4.0.

Enabling these backwards-incompatible features can complicate the downgrade process since you must remove any persisted backwards-incompatible features before you downgrade.

It is recommended that after upgrading, you allow your deployment to run without enabling these features for a burn-in period to ensure the likelihood of downgrade is minimal. When you are confident that the likelihood of downgrade is minimal, enable these features.

"4.0"

Available on MongoDB 4.0 and 4.2 Deployments

  • If set on MongoDB 4.0 deployments,

    Enables the 4.0 features that persist data incompatible with MongoDB 3.6.

    Enabling these backwards-incompatible features can complicate the downgrade process since you must remove any persisted backwards-incompatible features before you downgrade.

    It is recommended that after upgrading, you allow your deployment to run without enabling these features for a burn-in period to ensure the likelihood of downgrade is minimal. When you are confident that the likelihood of downgrade is minimal, enable these features.

  • If set on MongoDB 4.2 deployments,
    Disables the 4.2 features that persist data incompatible with MongoDB 4.0.
"3.6"

Available on MongoDB 3.6 and 4.0 Deployments

  • If set on MongoDB 3.6 deployments,

    Enables the 3.6 features that persist data incompatible with MongoDB 3.4.

    Enabling these backwards-incompatible features can complicate the downgrade process since you must remove any persisted backwards-incompatible features before you downgrade.

    It is recommended that after upgrading, you allow your deployment to run without enabling these features for a burn-in period to ensure the likelihood of downgrade is minimal. When you are confident that the likelihood of downgrade is minimal, enable these features.

  • If set on MongoDB 4.0 deployments,
    Disables the 4.0 features that persist data incompatible with MongoDB 3.6.
"3.4"

Available on MongoDB 3.4 and MongoDB 3.6 Deployments

"3.2"

Available on MongoDB 3.4 Deployments

Disables the 3.4 features that persist data incompatible with MongoDB 3.2.

Note
  • For a standalone, run the command on the standalone mongod instance.
  • For a replica set, run the command on the primary. A majority of the data-bearing members must be available.
  • For a sharded cluster, run the command on a mongos instance.

Certain background operations may prevent execution of setFeatureCompatibilityVersion. Use currentOp to identify any ongoing operations.

Deployments
featureCompatibilityVersion
For new 4.4 deployments
"4.4"
For 4.4 deployments upgraded from 4.2
"4.2" until you setFeatureCompatibilityVersion to "4.4".
For new 4.2 deployments
"4.2"
For 4.2 deployments upgraded from 4.0
"4.0" until you setFeatureCompatibilityVersion to "4.2".
For new 4.0 deployments
"4.0"
For 4.0 deployments upgraded from 3.6
"3.6" until you setFeatureCompatibilityVersion to "4.0".
For new 3.6 deployments
"3.6"
For 3.6 deployments upgraded from 3.4
"3.4" until you setFeatureCompatibilityVersion to "3.6".
For new 3.4 deployments
"3.4"
For 3.4 deployments upgraded from 3.2
"3.2" until you setFeatureCompatibilityVersion to "3.4".

This command must perform writes to an internal system collection. If for any reason the command does not complete successfully, you can safely retry the command as the operation is idempotent.

To view the featureCompatibilityVersion for a mongod instance, run the following command on a mongod instance:

Note

The operation is undefined on the mongos instances. For a sharded cluster that has access control enabled, to run the command against a member of the shard replica set, you must connect to the member as a shard local user.

db.adminCommand( { getParameter: 1, featureCompatibilityVersion: 1 } )

In the results document, the format of the featureCompatibilityVersion depends on the MongoDB version. Click on the tab for the appropriate MongoDB version.

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