What is the MongoDB cursor?

The Cursor is a MongoDB Collection of the document which is returned upon the find method execution. By default, it is automatically executed as a loop. In simple words when we call a find method, all the documents which are returned are saved in a virtual cursor.

What is cursor in mongoose?

In MongoDB parlance, a cursor is an object that you can use to iterate through the results of a query. Similarly, the MongoDB Node. js driver will return a cursor from find() . In most cases the cursor API is overkill, so mongoose hides it from you by default.

What is Pymongo cursor?

As we already discussed what is a cursor. It is basically a tool for iterating over MongoDB queries. This cursor instance is returned by the find() method. Consider the below example for better understanding.

What is Batchsize in MongoDB?

Cursor Batches The MongoDB server returns the query results in batches. Batch size will not exceed the maximum BSON document size. For most queries, the first batch returns 101 documents or just enough documents to exceed 1 megabyte. Subsequent batch size is 4 megabytes.

What is MongoDB getMore?

getMore. New in version 3.2. Use in conjunction with commands that return a cursor, e.g. find and aggregate , to return subsequent batches of documents currently pointed to by the cursor.

What is an AggregationCursor?

An AggregationCursor is a concurrency primitive for processing aggregation results one document at a time. It is analogous to QueryCursor. An AggregationCursor fulfills the Node. js streams3 API, in addition to several other mechanisms for loading documents from MongoDB one at a time.

What is cursor method?

The cursor method allows us to iterate through our database using a cursor, which will only execute a single query. While processing large amounts of data, the cursor method may be used to reduce your memory usage greatly.

Which of the following method returns a cursor?

3. Which of the following method returns true if the cursor has documents? Explanation: hasNext() returns true if the cursor returned by the db. collection.

What does $project do in MongoDB?

The $project takes a document that can specify the inclusion of fields, the suppression of the _id field, the addition of new fields, and the resetting of the values of existing fields. Adds a new field or resets the value of an existing field. Changed in version 3.6: MongoDB 3.6 adds the variable REMOVE .

What is batchSize?

Batch size is a term used in machine learning and refers to the number of training examples utilized in one iteration. Usually, a number that can be divided into the total dataset size.

What is batch size in DB?

During batch processing, write operations to the same database table are batched into statements according to the batch size. Batch size is the maximum number of write operations to include in a batch. When a transaction ends, all batches that did not exceed the batch size are also run.