MongoDB insertMany() Method

insertMany() inserts multiple documents in one operation, improving performance and efficiency.

• Adds many documents at once.
• Can be more efficient than single inserts depending on batch size, network conditions, and workload.
• Efficient for large datasets.

Syntax:

db.collection_name.insertMany([<document 1>, <document 2>, ...],{writeConcern: <document>,ordered: <boolean>})

• <document1>, <document2>, … : Array of documents to insert.
• writeConcern (optional): Overrides the default write concern.
• ordered (optional): true inserts in order (default); set false for unordered inserts.

Return Type of insertMany()

The insertMany() method returns an object that includes:

• acknowledged: A boolean that is true if the write concern was enabled, and false if it was disabled.
• insertedIds: An object containing the _id values of the inserted documents.

Examples of Using insertMany() in MongoDB

We’ll assume we’re working with a collection called student, which contains information about students such as their name and age.

Example 1: Insert Multiple Documents in a Single Operation without Specifying an _id field

We insert the array of documents that contains the name and age of the students.

Query:

db.student.insertMany([{name:"Ryan",age:20}, {name:"Ron",age:24}, {name:"Kim",age:26}])

Output:

Three documents are inserted into the student collection in a single operation.

Example 2: Insert Several Documents Specifying an _id Field

The query inserts multiple documents with custom _id values into the student collection, and MongoDB throws a duplicate key error if any _id already exists.

Query:

db.student.insertMany([{ _id: "stu200", name: "Luca", age: 20 }, { _id: "stu201", name: "Tim", age: 24 }])

Output:

The documents are inserted successfully with the given _id, preventing automatic ObjectId generation. If _id is duplicated, MongoDB will reject the insert operation for that document.

Error Handling

During bulk operations like insertMany(), MongoDB may throw a BulkWriteError (e.g., due to duplicate _id values), which can be handled using a try–catch block in application code.

• Duplicate Key Errors: Ensure no duplicates in unique indexed fields, and use { ordered: false } to continue inserting remaining documents despite errors.
• Validation Errors: Ensure all documents meet schema validation rules.
• Network Issues: Implement retry logic to handle transient network errors.
• Error Handling: Examine error details to understand and address specific issues.

var docs = [ /* array of documents */ ]
db.collection.insertMany(docs, { ordered: false })
 .then(result => console.log(result))
 .catch(error => {
 if (error.name === "BulkWriteError") {
 error.writeErrors.forEach(writeError => {
 console.error("Document index:", writeError.index);
 console.error("Error message:", writeError.errmsg);
 });
 } else {
 console.error("Unexpected error:", error);
 }
 });

This approach helps identify and handle BulkWriteError effectively.

Unordered Inserts

Unordered inserts in MongoDB allow remaining documents to be inserted even if some insert operations fail.

• Continues inserting documents despite individual failures.
• Prevents the entire operation from stopping due to one error.
• Implemented using insertMany() with ordered: false.
• Useful for bulk insert operations.

Query:

db.student.insertMany(
 [
 {_id:"stu203",name:"Sophia",age:28}, 
 {_id:"stu206", name:"Emma", age:25}
 ], 
 {ordered: false}
)

Output: