How to sort mongodb index

Sorting index is a type of MongoDB index that allows sorting documents in a collection by specific fields. Creating a sort index allows you to quickly sort query results without additional sorting operations. Advantages include quick sorting, override queries, and on-demand sorting. The syntax is db.collection.createIndex({ field: }), where is 1 (ascending order) or -1 (descending order). You can also create multi-field sorting indexes that sort multiple fields.

Sort of MongoDB indexes

Indexes are the key data structures in MongoDB that improve query performance. By creating an index of documents in a collection, queries can quickly find documents that meet certain criteria without scanning the entire collection.

Sort index

Sorting index is a type of MongoDB index that allows documents in a collection to be sorted by specific fields. This means that the query can use this field to sort its results without additional sorting operations after searching.

Create a sort index

To create a sort index, use the following syntax:

 <code>db.collection.createIndex({ field: <sort order> })</sort></code>

<sort order></sort> can be one of the following values:

• 1 : Ascending order
• -1 : Arrangement in descending order

For example, the following command creates a sorted index for name field in ascending order:

 <code>db.users.createIndex({ name: 1 })</code>

Using sorting index

When using sort indexes in a query, use the following syntax:

 <code>db.collection.find({}).sort({ field: <sort order> })</sort></code>

<sort order></sort> is the same as used when creating the index.

For example, the following query will retrieve all user documents in ascending order in name field:

 <code>db.users.find({}).sort({ name: 1 })</code>

Multi-field sorting index

MongoDB also supports creating composite sorting indexes that allow ordering multiple fields. The syntax is as follows:

 <code>db.collection.createIndex({ field1: <sort order>, field2: <sort order> })</sort></sort></code>

For example, the following command creates a composite sort index that arranges name field in descending order and age field in ascending order:

 <code>db.users.createIndex({ name: -1, age: 1 })</code>

Advantages

Using sorting indexes has the following advantages:

• Quick sort: Allows queries to return sorted results directly without additional sorting operations after searching.
• Override query: If both query conditions and sort fields are included in the index, the query engine can return the results through an index lookup without accessing the underlying collection. This can significantly improve query performance.
• Sort by Demand: MongoDB sorts the results only when needed, saving resources, especially when dealing with large collections.

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