What is a projection in MongoDB?

MongoDB provides a special feature that is known as Projection. It allows you to select only the necessary data rather than selecting whole data from the document. For example, a document contains 5 fields, i.e., { name: “Roma”, age: 30, branch: EEE, department: “HR”, salary: 20000 }

How does MongoDB sorting work?

To sort documents in MongoDB, you need to use sort() method. The method accepts a document containing a list of fields along with their sorting order. To specify sorting order 1 and -1 are used. 1 is used for ascending order while -1 is used for descending order.

What sorting algorithm does MongoDB use?

MongoDB can find the result of the sort operation using indexes. If MongoDB does not find sort order using index scanning, then it uses top-k sort algorithm.

How do I sort data in MongoDB?

Set the Sort Order

1. In the Query Bar, click Options.
2. Enter the sort document into the Sort field. To specify ascending order for a field, set the field to 1 in the sort document. To specify descending order for a field, set the field and -1 in the sort documents.
3. Click Find to run the query and view the updated results.

How projection is used in MongoDB compass?

To set a projection:

1. In the Query Bar, click Options.
2. Enter the projection document into the Project field. To include fields: Specify the field name and set to 1 in the project document.
3. Click Find to run the query and view the updated results. Note.

What is projection in Nodejs?

Projections limit the fields returned by the query.The projection document can specify the inclusion as well as exclusion of the fields as shows below: { field-name-1 : value , field-name-2 : value, ..,.., so on} here value can be either 1 or 0 where 1 signifies inclusion and 0 signifies exclusion.

What does sort do in Linux?

The sort command is used in Linux to print the output of a file in given order. This command processes on your data (the content of the file or output of any command) and reorders it in the specified way, which helps us to read the data efficiently.

Are MongoDB IDS sorted?

Sorting at query time uses CPU resources and delays the response to the application. However, when an index includes all fields used to select and sort the result set in proper order, MongoDB does not need to sort at query time. Instead, results are already sorted in the index, and can be returned immediately.

Which of the following sorting is not supported by MongoDB?

Explanation: MongoDB does not support collation-based sorting and is limited to byte-wise comparison via memcmp.

How do I project specific fields in MongoDB?

Starting in MongoDB 4.4, you can also specify embedded fields using the nested form, e.g. { item: 1, status: 1, size: { uom: 1 } } ….Return Specific Fields in Embedded Documents

1. The _id field (returned by default),
2. The item field,
3. The status field,
4. The uom field in the size document.

What is positional operator in MongoDB?

MongoDB – Positional Operator ($) This operator recognizes an element in an array to update without explicitly specifying the position of that item in the array.

Which field is always included in a projection unless specifically excluded?

The _id field is included automatically unless specifically excluded.