Compatibility Changes in MongoDB 7.0

Server and Drivers Compatibility Between Public Preview and GA

To use Queryable Encryption with equality queries, MongoDB server must be version 7.0 or later and drivers must be 7.0 compatible. If you are still using the Queryable Encryption Public Preview included with MongoDB 6.x, the server must remain on version 6.x and the drivers must be 6.x compatible. You cannot use MongoDB 6.x compatible drivers with a 7.0 server, or 7.0 compatible drivers with a 6.x server. Attempting to do so results in an error.

To make upgrading easier, MongoDB 7.0 drivers can decrypt data created with MongoDB 6.x drivers. For upgrade options, see the following sections.

OIDC Access Token Authentication Behavior

Starting in MongoDB 7.0, only one audience oidcIdentityProviders field can be specified for OIDC access tokens. audience fields with empty arrays or arrays of multiple strings are invalid.

For details, see oidcIdentityProviders Fields.

Granularity Settings

Starting in MongoDB 6.3, you can configure time series bucket granularity using the new bucketMaxSpanSeconds and bucketRoundingSeconds custom bucketing parameters. To downgrade below 6.3, you must either drop all collections with these parameters, or modify them to use the corresponding granularity. For details, see collMod.

Not all bucketMaxSpanSeconds and bucketRoundingSeconds values correspond to a granularity value. In such cases, you must drop the collection.

Partial TTL Indexes for Time Series Collections

Starting in MongoDB 6.3, you can create partial Time To Live (TTL) indexes on time series collections. To downgrade below 6.3, you must remove all partial TTL indexes from your time series collections.

config.settings Schema Validation

Starting in MongoDB 6.2, you must set value between 1 and 1024 (inclusive) when inserting or updating documents with the _id: chunksize field in the config.settings collection. If you specify an invalid value, MongoDB returns a schema validation error.

Any value fields outside the range of 1 to 1024 MB (inclusive) set prior to MongoDB 6.2 remain unchanged.

Removed Options

Starting in version 6.2, MongoDB removes the maxSize field from the addShard command. As a result:

• Running addShard with the maxSize field returns an InvalidOptions error.
• New documents in the shards collection no longer include the maxSize field.
• Any pre-existing maxSize field entries are ignored.

$add Floating Point Rounding Errors

Starting in MongoDB 6.1, when an $add expression receives an input list with multiple floating point values, MongoDB may return slightly different results compared to previous versions.

The $add expression no longer accounts for floating-point rounding errors. As a result, $add behaves like addition in most programming languages.

For example, the following $add expression returns a different result when run on MongoDB 6.1 compared to older versions:

db.test.aggregate(
   [
     {
        $project: {
           sumOfValues: {
              $add: [ 0.1, 0.2, 0.3 ]
           }
         }
      }
   ]
)

MongoDB 6.1 and later output:

[
  {
    _id: ObjectId("6390f8085425651d8d0ef0a7"),
    sumOfValues: 0.6000000000000001
  }
]

[
  {
    _id: ObjectId("6390f8085425651d8d0ef0a7"),
    sumOfValues: 0.6
  }
]

No Automatic Chunk Splitting

Starting in MongoDB 6.0.3, automatic chunk splitting is not performed. This is because of balancing policy improvements. Auto-splitting commands still exist, but do not perform an operation.

Starting in MongoDB 6.1, the following auto-splitting commands do not perform an operation:

• sh.enableAutoSplit()
• sh.disableAutoSplit()

Removed Options

Starting in MongoDB 6.1, journaling is always enabled. As a result, MongoDB removes the storage.journal.enabled option and the corresponding --journal and --nojournal command-line options.

Starting in MongoDB 6.1, SNMP is removed. All related command line options prevent mongod from starting. To monitor your deployment, use MongoDB Ops Manager.

Server Parameters

Starting in MongoDB 6.1, the default value for coordinateCommitReturnImmediatelyAfterPersistingDecision is false.

Sharding Metrics Changes

currentOp.opStatus is removed from the resharding metrics in MongoDB 6.1.

Views Not Permitted on Bucket Collection Namespace

You cannot create a view from a time series bucket collection namespace (namely, a collection prefixed with system.buckets).

If you are upgrading to MongoDB 6.1 from a prior version, you must drop all views which are created on system.buckets collections.