db.collection.bulkWrite()

Write Operations

db.collection.bulkWrite( [
   { insertOne : { "document" : <document> } }
] )

db.collection.bulkWrite([
   { replaceOne :
      {
         "filter" : <document>,
         "replacement" : <document>,
         "upsert" : <boolean>,
         "collation": <document>,                    // Available starting in 3.4
         "hint": <document|string>                   // Available starting in 4.2.1
      }
   }
] )

_id Field

If the document does not specify an _id field, then mongod adds the _id field and assign a unique ObjectId() for the document before inserting or upserting it. Most drivers create an ObjectId and insert the _id field, but the mongod will create and populate the _id if the driver or application does not.

If the document contains an _id field, the _id value must be unique within the collection to avoid duplicate key error.

Update or replace operations cannot specify an _id value that differs from the original document.

Execution of Operations

The ordered parameter specifies whether bulkWrite() will execute operations in order or not. By default, operations are executed in order.

The following code represents a bulkWrite() with five operations.

db.collection.bulkWrite(
   [
      { insertOne : <document> },
      { updateOne : <document> },
      { updateMany : <document> },
      { replaceOne : <document> },
      { deleteOne : <document> },
      { deleteMany : <document> }
   ]
)

In the default ordered : true state, each operation will be executed in order, from the first operation insertOne to the last operation deleteMany.

If ordered is set to false, operations may be reordered by mongod to increase performance. Applications should not depend on order of operation execution.

The following code represents an unordered bulkWrite() with six operations:

db.collection.bulkWrite(
   [
      { insertOne : <document> },
      { updateOne : <document> },
      { updateMany : <document> },
      { replaceOne : <document> },
      { deleteOne : <document> },
      { deleteMany : <document> }
   ],
   { ordered : false }
)

With ordered : false, the results of the operation may vary. For example, the deleteOne or deleteMany may remove more or fewer documents depending on whether the run before or after the insertOne, updateOne, updateMany, or replaceOne operations.

The number of operations in each group cannot exceed the value of the maxWriteBatchSize of the database. As of MongoDB 3.6, this value is 100,000. This value is shown in the hello.maxWriteBatchSize field.

This limit prevents issues with oversized error messages. If a group exceeds this limit, the client driver divides the group into smaller groups with counts less than or equal to the value of the limit. For example, with the maxWriteBatchSize value of 100,000, if the queue consists of 200,000 operations, the driver creates 2 groups, each with 100,000 operations.

Starting in MongoDB 3.6, once the error report for a single batch grows too large, MongoDB truncates all remaining error messages to the empty string. Currently, begins once there are at least 2 error messages with total size greater than 1MB.

The sizes and grouping mechanics are internal performance details and are subject to change in future versions.

Executing an ordered list of operations on a sharded collection will generally be slower than executing an unordered list since with an ordered list, each operation must wait for the previous operation to finish.

Capped Collections

bulkWrite() write operations have restrictions when used on a capped collection.

updateOne and updateMany throw a WriteError if the update criteria increases the size of the document being modified.

replaceOne throws a WriteError if the replacement document has a larger size than the original document.

deleteOne and deleteMany throw a WriteError if used on a capped collection.

Time Series Collections

bulkWrite() write operations have restrictions when used on a time series collection. Only insertOne can be used on time series collections. All other operations will return a WriteError.

Error Handling

db.collection.bulkWrite() throws a BulkWriteError exception on errors (unless the operation is part of a transaction on MongoDB 4.0). See Error Handling inside Transactions.

Excluding Write Concern errors, ordered operations stop after an error, while unordered operations continue to process any remaining write operations in the queue, unless when run inside a transaction. See Error Handling inside Transactions.

Write concern errors are displayed in the writeConcernErrors field, while all other errors are displayed in the writeErrors field. If an error is encountered, the number of successful write operations are displayed instead of the inserted _id values. Ordered operations display the single error encountered while unordered operations display each error in an array.

Transactions

db.collection.bulkWrite() can be used inside multi-document transactions.

Bulk Write Operations

The characters collection in the guidebook database contains the following documents:

{ "_id" : 1, "char" : "Brisbane", "class" : "monk", "lvl" : 4 },
{ "_id" : 2, "char" : "Eldon", "class" : "alchemist", "lvl" : 3 },
{ "_id" : 3, "char" : "Meldane", "class" : "ranger", "lvl" : 3 }

The following bulkWrite() performs multiple operations on the collection:

try {
   db.characters.bulkWrite([
      { insertOne: { "document": { "_id": 4, "char": "Dithras", "class": "barbarian", "lvl": 4 } } },
      { insertOne: { "document": { "_id": 5, "char": "Taeln", "class": "fighter", "lvl": 3 } } },
      { updateOne : {
         "filter" : { "char" : "Eldon" },
         "update" : { $set : { "status" : "Critical Injury" } }
      } },
      { deleteOne : { "filter" : { "char" : "Brisbane"} } },
      { replaceOne : {
         "filter" : { "char" : "Meldane" },
         "replacement" : { "char" : "Tanys", "class" : "oracle", "lvl": 4 }
      } }
   ]);
} catch (e) {
   print(e);
}

The operation returns the following:

{
   "acknowledged" : true,
   "deletedCount" : 1,
   "insertedCount" : 2,
   "matchedCount" : 2,
   "upsertedCount" : 0,
   "insertedIds" : {
      "0" : 4,
      "1" : 5
   },
   "upsertedIds" : {
   }
}

If the collection had contained a document with "_id" : 5" before executing the bulk write, then when the bulk write is executed, the following duplicate key exception would be thrown for the second insertOne:

BulkWriteError({
   "writeErrors" : [
      {
         "index" : 1,
         "code" : 11000,
         "errmsg" : "E11000 duplicate key error collection: guidebook.characters index: _id_ dup key: { _id: 5.0 }",
         "op" : {
            "_id" : 5,
            "char" : "Taeln",
            "class" : "fighter",
            "lvl" : 3
         }
      }
   ],
   "writeConcernErrors" : [ ],
   "nInserted" : 1,
   "nUpserted" : 0,
   "nMatched" : 0,
   "nModified" : 0,
   "nRemoved" : 0,
   "upserted" : [ ]
})

Since ordered is true by default, only the first operation completes successfully. The rest are not executed. Running the bulkWrite() with ordered : false would allow the remaining operations to complete despite the error.

Unordered Bulk Write

The characters collection in the guidebook database contains the following documents:

{ "_id" : 1, "char" : "Brisbane", "class" : "monk", "lvl" : 4 },
{ "_id" : 2, "char" : "Eldon", "class" : "alchemist", "lvl" : 3 },
{ "_id" : 3, "char" : "Meldane", "class" : "ranger", "lvl" : 3 }

The following bulkWrite() performs multiple unordered operations on the characters collection. Note that one of the insertOne stages has a duplicate _id value:

try {
   db.characters.bulkWrite([
      { insertOne: { "document": { "_id": 4, "char": "Dithras", "class": "barbarian", "lvl": 4 } } },
      { insertOne: { "document": { "_id": 4, "char": "Taeln", "class": "fighter", "lvl": 3 } } },
      { updateOne : {
         "filter" : { "char" : "Eldon" },
         "update" : { $set : { "status" : "Critical Injury" } }
      } },
      { deleteOne : { "filter" : { "char" : "Brisbane"} } },
      { replaceOne : {
         "filter" : { "char" : "Meldane" },
         "replacement" : { "char" : "Tanys", "class" : "oracle", "lvl": 4 }
      } }
   ], { ordered : false } );
} catch (e) {
   print(e);
}

The operation returns the following:

BulkWriteError({
   "writeErrors" : [
      {
         "index" : 1,
         "code" : 11000,
         "errmsg" : "E11000 duplicate key error collection: guidebook.characters index: _id_ dup key: { _id: 4.0 }",
         "op" : {
            "_id" : 4,
            "char" : "Taeln",
            "class" : "fighter",
            "lvl" : 3
         }
      }
   ],
   "writeConcernErrors" : [ ],
   "nInserted" : 1,
   "nUpserted" : 0,
   "nMatched" : 2,
   "nModified" : 2,
   "nRemoved" : 1,
   "upserted" : [ ]
})

Since this was an unordered operation, the writes remaining in the queue were processed despite the exception.

Bulk Write with Write Concern

The enemies collection contains the following documents:

{ "_id" : 1, "char" : "goblin", "rating" : 1, "encounter" : 0.24 },
{ "_id" : 2, "char" : "hobgoblin", "rating" : 1.5, "encounter" : 0.30 },
{ "_id" : 3, "char" : "ogre", "rating" : 3, "encounter" : 0.2 },
{ "_id" : 4, "char" : "ogre berserker" , "rating" : 3.5, "encounter" : 0.12}

The following bulkWrite() performs multiple operations on the collection using a write concern value of "majority" and timeout value of 100 milliseconds:

try {
   db.enemies.bulkWrite(
      [
         { updateMany :
            {
               "filter" : { "rating" : { $gte : 3} },
               "update" : { $inc : { "encounter" : 0.1 } }
            },
         },
         { updateMany :
            {
               "filter" : { "rating" : { $lt : 2} },
               "update" : { $inc : { "encounter" : -0.25 } }
            },
         },
         { deleteMany : { "filter" : { "encounter": { $lt : 0 } } } },
         { insertOne :
            {
               "document" :
                  {
                     "_id" :5, "char" : "ogrekin" , "rating" : 2, "encounter" : 0.31
                  }
            }
         }
      ],
      { writeConcern : { w : "majority", wtimeout : 100 } }
   );
} catch (e) {
   print(e);
}

If the total time required for all required nodes in the replica set to acknowledge the write operation is greater than wtimeout, the following writeConcernError is displayed when the wtimeout period has passed.

BulkWriteError({
   "writeErrors" : [ ],
   "writeConcernErrors" : [
      {
         "code" : 64,
         "codeName" : "WriteConcernFailed",
         "errmsg" : "waiting for replication timed out",
         "errInfo" : {
            "wtimeout" : true
         }
      },
      {
         "code" : 64,
         "codeName" : "WriteConcernFailed",
         "errmsg" : "waiting for replication timed out",
         "errInfo" : {
            "wtimeout" : true
         }
      },
      {
         "code" : 64,
         "codeName" : "WriteConcernFailed",
         "errmsg" : "waiting for replication timed out",
         "errInfo" : {
            "wtimeout" : true
         }
      }
   ],
   "nInserted" : 1,
   "nUpserted" : 0,
   "nMatched" : 4,
   "nModified" : 4,
   "nRemoved" : 1,
   "upserted" : [ ]
})

The result set shows the operations executed since writeConcernErrors errors are not an indicator that any write operations failed.