What is projection explain how do you use projection in MongoDB with example?

What is a projection in MongoDB

In MongoDB, projection refers to choosing only the relevant data from a document rather than all of its data. For example, if a document has 5 fields but you only need to show 3, then choose only those 3 fields.

What is the function of projection in MongoDB

MongoDB projection allows you to project concise and transparent data, filter the data set without affecting the database performance, and extract only the fields you need from a document—not all fields.

How projection is used in MongoDB compass

To set a projection:

1. To access options, click the Query Bar.
2. To include fields: Specify the field name and set to 1 in the project document. Enter the projection document into the Project field.
3. To run the search and see the revised results, click Find.

Which of the following command is used for projection in MongoDB

The projection parameter, which is used to specify which fields are returned in the matching documents, can be used with the db. collection. find() method, which takes two parameters.

Which of the following is not a projection operator in MongoDB

The following projection operators are not supported by find() operations on views: $ $elemMatch. $slice.

What is MongoDB elemMatch

The $elemMatch operator matches documents that have an array field with at least one element that satisfies each of the specified query criteria.

What is sharding in MongoDB

In MongoDB, sharding is accomplished by dividing large data sets into small data sets and distributing them across multiple MongoDB instances. November 11, 2020

What is MongoDB indexing

These multikey indexes allow queries to select documents that contain arrays by matching on element or elements of the arrays. If you index a field that holds an array value, MongoDB creates separate index entries for every element of the array.

How do I find one record in MongoDB

The findOne() method in MongoDB locates and returns a single document that satisfies the given selection criteria. If more than one document satisfies the query expression, this method will return the first document in the order that the documents appear on the disk.

How do I capture a specific field in MongoDB

With the following syntax, you can choose a single field in MongoDB: db. yourCollectionName. find(yourFieldName:yourValue,yourSingleFieldName:1,_id:0);

When should I use aggregate in MongoDB

You can use aggregation operations to: Group values from multiple documents together. Perform operations on the grouped data to return a single result.
Aggregation Pipelines

1. The input documents are subjected to an operation at each stage.
2. The output documents from one stage are transferred to the following stage.

How do I join two collections in MongoDB

The $lookup operator is a stage that executes a left outer join with another collection and helps filter data from joined documents. For instance, if a user needs all grades from all students, then the following query can be written: Students.Feb 14, 2022

What is embedded document in MongoDB

Nested documents are those types of documents that contain a document inside another document, and MongoDB offers you a cool feature known as embedded or nested documents.Sep 14, 2021

What is skip in MongoDB

It basically eliminates the first n documents from the result set.MongoDB – skip() Method In MongoDB, the skip() method will skip the first n document from the query result, you just need to pass the number of records/documents to be skipped.Jan. 28, 2021

What is the name of the default file used to configure MongoDB

File Format YAML is the format used by MongoDB configuration files [1].

What is Upsert MongoDB

Or, to put it another way, upsert is a combination of update and insert (update insert = upsert) and is a MongoDB option that is used for update operations such as update(), findAndModify(), etc.

What does a MongoDB collection consists of

In the MongoDB database, a document is a representation of a single entity of data, and a collection is a grouping of related objects. This is a significant distinction between MongoDB and SQL, as row data in SQL is flat, with one column for each value in the row.Sep 18, 2014

How do I sort in MongoDB

Use the sort() method to arrange documents in ascending or descending order in MongoDB. The method takes a document containing a list of fields and the order in which they should be arranged, and it accepts two arguments: 1 for ascending order and -1 for descending order.