Transactions and Operations

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Operations Supported in Multi-Document Transactions

CRUD Operations
Count Operation
Distinct Operation
Administration Operations
Informational Operations
Restricted Operations

This version of the documentation is archived and no longer supported. To upgrade your 5.0 deployment, see the MongoDB 6.0 upgrade procedures.

For transactions:

You can create collections and indexes in transactions. For details, see Create Collections and Indexes in a Transaction
The collections used in a transaction can be in different databases.
Note
You cannot create new collections in cross-shard write transactions. For example, if you write to an existing collection in one shard and implicitly create a collection in a different shard, MongoDB cannot perform both operations in the same transaction.
You cannot write to capped collections.
You cannot use read concern "snapshot" when reading from a capped collection. (Starting in MongoDB 5.0)
You cannot read/write to collections in the config, admin, or local databases.
You cannot write to system.* collections.
You cannot return the supported operation's query plan using explain or similar commands.

For cursors created outside of a transaction, you cannot call getMore inside the transaction.
For cursors created in a transaction, you cannot call getMore outside the transaction.

You cannot specify the killCursors command as the first operation in a transaction.
Additionally, if you run the killCursors command within a transaction, the server immediately stops the specified cursors. It does not wait for the transaction to commit.

Operations Supported in Multi-Document Transactions

CRUD Operations

The following read/write operations are allowed in transactions:

Method	Command	Note
`db.collection.aggregate()`	`aggregate`	Excluding the following stages: `$collStats` `$currentOp` `$indexStats` `$listLocalSessions` `$listSessions` `$merge` `$out` `$planCacheStats` `$unionWith`
`db.collection.countDocuments()`		Excluding the following query operator expressions: `$where` `$near` `$nearSphere` The method uses the `$match` aggregation stage for the query and `$group` aggregation stage with a `$sum` expression to perform the count.
`db.collection.distinct()`	`distinct`	Available on unsharded collections. For sharded collections, use the aggregation pipeline with the `$group` stage. See Distinct Operation.
`db.collection.find()`	`find`
`db.collection.deleteMany()` `db.collection.deleteOne()` `db.collection.remove()`	`delete`
`db.collection.findOneAndDelete()` `db.collection.findOneAndReplace()` `db.collection.findOneAndUpdate()`	`findAndModify`	If the update or replace operation is run with `upsert: true` on a non-existing collection, the collection is implicitly created. For more details, see Administration Operations.
`db.collection.insertMany()` `db.collection.insertOne()`	`insert`	If run on a non-existing collection, the collection is implicitly created. For more details, see Administration Operations.
`db.collection.updateOne()` `db.collection.updateMany()` `db.collection.replaceOne()`	`update`	If run on a non-existing collection, the collection is implicitly created. For more details, see Administration Operations.
`db.collection.bulkWrite()` Various Bulk Operation Methods		If run on a non-existing collection, the collection is implicitly created. For more details, see Administration Operations.

Note

Updates to Shard Key Values

You can update a document's shard key value (unless the shard key field is the immutable _id field) by issuing single-document update / findAndModify operations either in a transaction or as a retryable write. For details, see Change a Document's Shard Key Value.

Count Operation

To perform a count operation within a transaction, use the $count aggregation stage or the $group (with a $sum expression) aggregation stage.

MongoDB drivers provide a collection-level API countDocuments(filter, options) as a helper method that uses the $group with a $sum expression to perform a count.

mongosh provides the db.collection.countDocuments() helper method that uses the $group with a $sum expression to perform a count.

Distinct Operation

To perform a distinct operation within a transaction:

For unsharded collections, you can use the db.collection.distinct() method/the distinct command as well as the aggregation pipeline with the $group stage.
For sharded collections, you cannot use the db.collection.distinct() method or the distinct command.
To find the distinct values for a sharded collection, use the aggregation pipeline with the $group stage instead. For example:
- Instead of db.coll.distinct("x"), use
  db.coll.aggregate([ { $group: { _id: null, distinctValues: { $addToSet: "$x" } } }, { $project: { _id: 0 } } ])
- Instead of db.coll.distinct("x", { status: "A" }), use:
  db.coll.aggregate([ { $match: { status: "A" } }, { $group: { _id: null, distinctValues: { $addToSet: "$x" } } }, { $project: { _id: 0 } } ])
The pipeline returns a cursor to a document:
```
{ "distinctValues" : [ 2, 3, 1 ] }
```
Iterate the cursor to access the results document.

Administration Operations

You can create collections and indexes inside a distributed transaction if the transaction is not a cross-shard write transaction.

Explicit Create Operations

Command	Method	Notes
`create`	`db.createCollection()`	See also the Implicit Create Operations.
`createIndexes`	`db.collection.createIndex()` `db.collection.createIndexes()`	The index to create must either be on a non-existing collection, in which case, the collection is created as part of the operation, or on a new empty collection created earlier in the same transaction.

Note

For explicit creation of a collection or an index inside a transaction, the transaction read concern level must be "local".

For more information on creating collections and indexes in a transaction, see Create Collections and Indexes in a Transaction.

Implicit Create Operations

You can also implicitly create a collection through the following write operations against a non-existing collection:

Method Run against Non-Existing Collection	Command Run against Non-Existing Collection
`db.collection.findAndModify()` with `upsert: true` `db.collection.findOneAndReplace()` with `upsert: true` `db.collection.findOneAndUpdate()` with `upsert: true`	`findAndModify` with `upsert: true`
`db.collection.insertMany()` `db.collection.insertOne()`	`insert`
`db.collection.updateOne()` with `upsert: true` `db.collection.updateMany()` with `upsert: true` `db.collection.replaceOne()` with `upsert: true`	`update` with `upsert: true`
`db.collection.bulkWrite()` with insert or `upsert:true` operations Various Bulk Operation Methods with insert or `upsert:true` operations

For other CRUD operations allowed in transactions, see CRUD Operations.

For more information on creating collections and indexes in a transaction, see Create Collections and Indexes in a Transaction.

Informational Operations

Informational commands, such as hello, buildInfo, connectionStatus (and their helper methods) are allowed in transactions; however, they cannot be the first operation in the transaction.

Restricted Operations

The following operations are not allowed in transactions:

Creating new collections in cross-shard write transactions. For example, if you write to an existing collection in one shard and implicitly create a collection in a different shard, MongoDB cannot perform both operations in the same transaction.
Explicit creation of collections, e.g. db.createCollection() method, and indexes, e.g. db.collection.createIndexes() and db.collection.createIndex() methods, when using a read concern level other than "local".
The listCollections and listIndexes commands and their helper methods.
Other non-CRUD and non-informational operations, such as createUser, getParameter, count, etc. and their helpers.