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snapshot on Capped Collectionslocal is the Default Read Concerncursor.map() Return TypelistDatabases Output ChangesThe following 5.0 changes can affect compatibility with older versions of MongoDB.
Starting in MongoDB 5.0, certain database commands raise an error if passed a parameter not explicitly accepted by the command. In MongoDB 4.4 and earlier, unrecognized parameters are silently ignored.
Affected Commands:
Starting in MongoDB 5.0, these database commands and mongo shell helper methods are removed:
| Removed Command | Alternative |
|---|---|
db.collection.copyTo() | $out |
db.collection.ensureIndex() | db.collection.createIndex() |
db.collection.save() | |
db.resetError() | Not available |
geoSearch | One of the Geospatial Query Operators |
Mongo.getSecondaryOk() | Mongo.getReadPrefMode() |
Mongo.isCausalConsistency | Not available |
Mongo.setSecondaryOk() | Mongo.setReadPref() |
rs.secondaryOk() | Mongo.setReadPref() |
resetError | Not available |
shardConnPoolStats | connPoolStats |
unsetSharding | Not available |
MongoDB 5.0 removes the following server parameters:
| Removed Parameters | |
|---|---|
cachePressureThreshold | MongoDB 5.0 removes the cachePressureThreshold server parameter. Due to changes in how WiredTiger calculates snapshot window size this parameter is no longer relevant.
|
shouldMultiDocTxnCreateCollectionAndIndexes | MongoDB 5.0 removes the shouldMultiDocTxnCreateCollectionAndIndexes server parameter. In 5.0+, collection and index creation inside of transactions is always enabled. You can no longer use the server parameter to disable this behavior.
|
MongoDB 5.0 removes the deprecated geoHaystack index. Use a 2d index instead.
Upgrading your MongoDB instance to 5.0 and setting featureCompatibilityVersion to 5.0 will delete any pre-existing geoHaystack indexes.
Starting in MongoDB 5.0, the serverStatus command does not output opReadConcernCounters, which contained the read concern level specified by query operations. Instead, the new readConcernCounters replaces opReadConcernCounters and contains additional information.
Starting in MongoDB 5.0, the serverStatus command does not output the cache pressure percentage threshold and the current cache pressure percentage under wiredTiger.snapshot-window-settings.
currentOp Output ChangeStarting in MongoDB 5.0, the $currentOp.remainingOperationTimeEstimated metric is only present on the recipient shard when a resharding operation is taking place.
The mongo shell has been deprecated in MongoDB v5.0. The replacement shell is mongosh.
Shell packaging also changes in MongoDB v5.0. Refer to the installation instructions for further details.
enableMajorityReadConcern Is Not ConfigurableStarting in MongoDB 5.0, enableMajorityReadConcern and --enableMajorityReadConcern cannot be changed and are always set to true due to storage engine improvements.
In earlier versions of MongoDB, enableMajorityReadConcern and --enableMajorityReadConcern are configurable and can be set to false to prevent storage cache pressure from immobilizing a deployment with a three-member primary-secondary-arbiter (PSA)
architecture.
If you are using a three-member primary-secondary-arbiter (PSA)
architecture, the write concern "majority" can cause performance issues if a secondary is unavailable or lagging. See Mitigate Performance Issues with PSA Replica Set for advice on how to mitigate these issues.
secondaryDelaySecs Configuration SettingStarting in MongoDB 5.0, secondaryDelaySecs replaces slaveDelay. This change is not backwards compatible.
To configure cluster nodes for split horizon DNS, use host names instead of IP addresses.
Starting in MongoDB v5.0, replSetInitiate and replSetReconfig reject configurations that use IP addresses instead of hostnames.
Use disableSplitHorizonIPCheck to modify nodes that cannot be updated to use host names. The parameter only applies to the configuration commands.
mongod and mongos do not rely on disableSplitHorizonIPCheck for validation at startup. Legacy mongod and mongos instances that use IP addresses instead of host names will start after an upgrade.
Instances that are configured with IP addresses log a warning to use host names instead of IP addresses.
config.transactionsStarting in MongoDB 5.0, non-transaction reads are not allowed on the config.transactions collection with the following read concerns and options:
"snapshot""majority" and the afterClusterTime option is set"majority" within a causally consistent sessionStarting in MongoDB 5.0, it is no longer possible to perform manual write operations to the oplog on a cluster running as a replica set. Performing write operations to the oplog when running as a standalone instance should only be done with guidance from MongoDB Support.
Starting in MongoDB 5.0, a newly added secondary does not count as a voting member and cannot be elected until it has reached the SECONDARY state.
When a new voting node is added to a replica set, replSetReconfig will internally add a newlyAdded field to the node's configuration. Nodes with the newlyAdded field do not count towards the current number of voting nodes. When initial sync completes and the node reaches SECONDARY state, the newlyAdded field is automatically removed.
newlyAdded will error even if run with { force: true }.newlyAdded field, using rs.reconfig() to change the configuration will not remove the newlyAdded field. The newlyAdded field will be appended to the user provided configuration.replSetGetConfig will remove any newlyAdded fields from its output. If you would like to see any newlyAdded fields, you can query the local.system.replset collection directly.Starting in MongoDB 5.0, you cannot specify a default write concern with settings.getLastErrorDefaults other than the default of { w: 1, wtimeout: 0 } . Instead, use the setDefaultRWConcern command to set the default read or write concern configuration for a replica set or sharded cluster.
snapshot on Capped CollectionsStarting in MongoDB 5.0, you cannot use read concern "snapshot" when reading from a capped collection.
local is the Default Read ConcernStarting in MongoDB 5.0, "local" is the default read concern level for read operations against the primary and secondaries.
This may introduce a significant latency increase for count queries that use a filter and for covered queries.
You can opt out of this behavior by setting the cluster-wide read concern with setDefaultRWConcern.
cursor.map() Return Typecursor.map() returned an Array in the legacy mongo shell. The return type is Cursor in mongosh. You can use .toArray() to convert the results.
Starting in MongoDB 5.0, mongod no longer raises an error when you use the following update operators with an empty operand expression ( { } ):
$addToSet$bit$currentDate$inc$max$min$mul$pop$pull$pullAll$push$rename$set$setOnInsert$unsetAn empty update results in no changes and no oplog entry is created (meaning that the operation is a no-op).
Starting in MongoDB 5.0, update operators process document fields with string-based names in lexicographic order. Fields with numeric names are processed in numeric order. See Update Operators Behavior for details.
The following aggregation pipeline operators now have a 64-bit integer value maximum limit.
If you pass a value that exceeds this limit, the pipeline returns an invalid argument error.
listDatabases Output ChangesStarting in MongoDB 5.0, output from the listDatabases command running against a mongod is more consistent with output from listDatabases running against a mongos.
The following table shows the differences in data types for listDatabases output fields between MongoDB 5.0 and earlier versions. Only fields which differ between 5.0 and earlier versions are listed.
| Type in MongoDB 5.0 | Type in MongoDB 4.4 and earlier (mongod) | Type in MongoDB 4.4 and earlier (mongos) | |
|---|---|---|---|
sizeOnDisk | integer | double | integer |
totalSize | integer | double | integer |
totalSizeMb | integer | not present (see below) | integer |
The output from listDatabases now includes the totalSizeMb field when run against either a mongos or a mongod. In MongoDB 4.4 and earlier, totalSizeMb only appears when run against mongos. totalSizeMb is the sum of the sizeOnDisk fields, expressed in megabytes.
When run against mongos, the shards field in the listDatabases output contains a field-value pair for each collection on a particular shard. Size values in the shards field are expressed as integers.
Starting in MongoDB 5.0, mongod and mongos now issue a startup warning when their certificates do not include a Subject Alternative Name attribute.
The following platforms do not support common name validation:
Clients using these platforms will not authenticate to MongoDB servers that use x.509 certificates whose hostnames are specified by CommonName attributes.
Starting in version 5.0, MongoDB deprecates the map-reduce operation.
For examples of aggregation pipeline alternatives to map-reduce operations, see Map-Reduce to Aggregation Pipeline and Map-Reduce Examples.
MongoDB 5.0 adds auditing capabilities that can be configured at runtime.
If auditLog.runtimeConfiguration is set to true, then the mongod and mongos configuration files can no longer set setParameter.auditAuthorizationSuccess or configure audit filters. If the server configuration files contain these settings the server will fail to start and will log an error.
If auditLog.runtimeConfiguration is set to false and an audit filter config document is present, then a startup warning will be issued but the server will not abort.
Starting in MongoDB 5.0, if you change the transactionLifetimeLimitSeconds parameter, you must also change transactionLifetimeLimitSeconds to the same value on all config server replica set members. Keeping this value consistent:
Starting in MongoDB 5.0:
"5.0" or greater, users can no longer write directly to the <database>.system.views collection.reIndex command and the db.collection.reIndex() shell method may only be run on standalone instances.directoryPerDB or --directoryperdb is enabled deletes the newly empty subdirectory for that database.$subtract aggregation operator will convert the data type of the result if necessary to accurately represent the result value. See $subtract for the specific conversions. This change also applies to MongoDB 4.4.3+, 4.2.12+, 4.0.22+, and 3.6.22+.--serviceExecutor command-line option and the corresponding net.serviceExecutor configuration option.--apiStrict option is set. Attempting to authenticate as a new user while currently logged in as an existing user when the --apiStrict option is set will generate an error message once per authentication attempt. If you are not using the --apiStrict option, authenticating as a new user while currently logged in as an existing user will write a warning to the log once per authentication attempt.$text indexes.setDefaultRWConcern command.replSetOplog size in mongosh, use the Double() constructor with the replSetResizeOplog command.| Deprecated | |
|---|---|
mongo | The legacy mongo shell has been deprecated in MongoDB v5.0. The replacement is mongosh.
|
db.printSlaveReplicationInfo() | Deprecated since version 4.4.1: Use |
rs.printSlaveReplicationInfo() | Deprecated since version 4.4.1: Use |
security.clusterIpSourceWhitelist | Deprecated in version 5.0: Use security.clusterIpSourceAllowlist instead.
|
--clusterIpSourceWhitelist | Deprecated in version 5.0: Use --clusterIpSourceAllowlist instead.
|
logout | Deprecated in version 5.0: Disconnect from the server to end your session instead. |
db.logout() | Deprecated in version 5.0: Disconnect from the server to end your session instead. |
| local audit message field | Deprecated in version 5.0: Use the localEndpoint field in the clientMetadata audit message instead.
|
MongoDB 5.0 deprecates the following wire protocol opcodes:
OP_REPLYOP_UPDATEOP_INSERTOP_QUERYOP_GET_MOREOP_DELETEOP_KILL_CURSORSNewer driver versions use OP_MSG instead of these deprecated opcodes.
The related commands and methods are also deprecated in MongoDB 5.0:
getLastErrordb.getLastError()db.getLastErrorObj()To ensure your driver uses the most up-to-date wire protocol, upgrade your driver to a 5.0-compatible version.
Any code explicitly using getLastError, db.getLastError(), or db.getLastErrorObj() should instead use the CRUD API to issue the write with the desired write concern. Information about the success or failure of the write operation will be provided directly by the driver as a return value.
Some features in 5.0 require not just the 5.0 binaries but the featureCompatibilityVersion (fCV) set to 5.0. These features include:
. and $ in field names requires fCV set to 5.0+.