What is the batch size in MongoDB #database #wecommit100xshare

In MongoDB, batch size refers to the number of documents returned by a query or cursor in one network round trip from the database server to the client. Adjusting the batch size can help optimize performance, especially when dealing with large datasets.

The default initial batch size is 101 documents.

Here are a few ways to specify the batch size in MongoDB:

Using the batchSize Method: When you execute a query and get a cursor, you can use the batchSize method to set the number of documents returned in each batch.

# javascript
db.collection.find().batchSize(50);        

In Aggregation Framework: When using the aggregation framework, you can specify the batch size in the $cursor stage.

# javascript
db.collection.aggregate([
    { $match: { status: "A" } },
    { $sort: { amount: -1 } },
    { $cursor: { batchSize: 50 } }
]);        

Using MongoDB Drivers: Most MongoDB drivers (like the Node.js driver, Python's PyMongo, etc.) provide options to set the batch size when iterating over a cursor. For example, in PyMongo:

Using the find Command with batchSize: You can directly pass the batchSize option in the find command:

# javascript
db.collection.find({}, { batchSize: 50 });        

By setting an appropriate batch size, you can control memory usage and the number of network trips, which can lead to performance improvements in your application.