Compound Indexes

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Overview

Compound indexes hold references to multiple fields within a collection's documents, improving query and sort performance.

When creating a compound index, you must specify the following:

The fields on which to create the index
The sort order for each field (ascending or descending)

Sample Data

The examples in this guide use the movies collection in the sample_mflix database from the Atlas sample datasets. To learn how to create a free MongoDB deployment and load the sample datasets, see the MongoDB Get Started guide.

The following Kotlin data class models the documents in this collection:

data class Movie(
    @BsonId
    val id: ObjectId,
    val title: String? = "",
    val type: String? = "",
    val genres: List<String>? = null,
    val cast: List<String>? = null,
    val plot: String? = "",
)

Create a Compound Index

The following example creates a compound index on the type and genre fields, with both fields indexed in ascending order:

collection.createIndex(Indexes.ascending(Movie::type.name, Movie::genres.name))

The following is an example of a query that uses the index created in the preceding code sample:

val filter = and(
    eq(Movie::type.name, "movie"),
    `in`(Movie::genres.name, "Drama")
)
val sort = Sorts.ascending(Movie::type.name, Movie::genres.name)
val results = collection.find(filter).sort(sort)
results.forEach { result ->
    println(result)
}

Movie(id=573a1392f29313caabcda755, title=China Seas, type=movie, genres=[Action, Drama, Adventure], ...)
Movie(id=573a1392f29313caabcd9ca6, title=Scarface, type=movie, genres=[Action, Crime, Drama], ... )
Movie(id=573a1392f29313caabcdb258, title=The Hurricane, type=movie, genres=[Action, Drama, Romance], ...)
Movie(id=573a1391f29313caabcd820b, title=Beau Geste, type=movie, genres=[Action, Adventure, Drama], ...)
...

Additional Information

To learn more about compound indexes, see Compound Indexes in the MongoDB Server manual.

To learn about effective indexing strategies using compound indexes, see The ESR Rule in the MongoDB Server manual.

API Documentation

To learn more about any of the methods discussed in this guide, see the following API documentation:

Back

Single-Field Indexes

Atlas Search Indexes