Optimize Queries by Using Indexes

Overview

On this page, you can see copyable code examples that show how to manage different types of indexes by using the MongoDB Scala Driver.

To use an example from this page, copy the code example into the sample application or your own application. Be sure to replace all placeholders in the code examples, such as <connection string URI>, with the relevant values for your MongoDB deployment.

import org.mongodb.scala._
import org.mongodb.scala.model.SearchIndexModel
import java.util.concurrent.TimeUnit
import scala.concurrent.Await
import scala.concurrent.duration.Duration
import org.mongodb.scala.model.Indexes
object SearchIndexes {
  def main(args: Array[String]): Unit = {
    // Create a new client and connect to the server
    val mongoClient = MongoClient("<connection string URI>")
    val database = mongoClient.getDatabase("<database name>")
    val collection = database.getCollection("<collection name>")
    // Start example code here
    
    // End example code here
    Thread.sleep(1000)
    mongoClient.close()
  }
}

Single Field Index

The following example creates an ascending index on the specified field:

val index = Indexes.ascending("<field name>")
val observable = collection.createIndex(index)
Await.result(observable.toFuture(), Duration(10, TimeUnit.SECONDS))

To learn more about single field indexes, see the Single Field Indexes guide.

Compound Index

The following example creates a compound index on the two specified fields.

val index = Indexes.compoundIndex(
    Indexes.descending("<field name 1>"), 
    Indexes.ascending("<field name 2>")
)
val observable = collection.createIndex(index)
Await.result(observable.toFuture(), Duration(10, TimeUnit.SECONDS))

To learn more about compound indexes, see the Compound Indexes guide.

Multikey Index

The following example creates a multikey index on the specified array-valued field:

val index = Indexes.ascending("<field name>")
val observable = collection.createIndex(index)
Await.result(observable.toFuture(), Duration(10, TimeUnit.SECONDS))

To learn more about multikey indexes, see the Multikey Indexes guide.

Geospatial Index

The following example creates a 2dsphere index on the specified field that contains GeoJSON objects:

val observable = collection.createIndex(Indexes.geo2dsphere("<2d index>"))
Await.result(observable.toFuture(), Duration(10, TimeUnit.SECONDS))

For more information on 2dsphere indexes, see the 2dsphere Indexes guide in the MongoDB Server manual.

For more information about the GeoJSON type, see the GeoJSON Objects guide in the MongoDB Server manual.

Drop Index

The following example deletes an index with the specified name:

val observable = collection.dropIndex("<index name>")
Await.result(observable.toFuture(), Duration(10, TimeUnit.SECONDS))

Atlas Search Index Management

The following sections contain code examples that describe how to manage Atlas Search indexes.

To learn more about search indexes, see the Atlas Search Indexes guide.

val index = Document("mappings" -> Document("dynamic" -> <boolean value>))
val observable = collection.createSearchIndex("<index name>", index)
Await.result(observable.toFuture(), Duration(10, TimeUnit.SECONDS))

val observable = collection.listSearchIndexes()
observable.subscribe(new Observer[Document] {
    override def onNext(index: Document): Unit = println(index.toJson())
    override def onError(e: Throwable): Unit = println("Error: " + e.getMessage)
    override def onComplete(): Unit = println("Completed")
})

val updateIndex = Document("mappings" -> Document("dynamic" -> false))
val observable = collection.updateSearchIndex("<index to update>", updateIndex)
Await.result(observable.toFuture(), Duration(10, TimeUnit.SECONDS))

val observable = collection.dropSearchIndex("<index name>")
Await.result(observable.toFuture(), Duration(10, TimeUnit.SECONDS))

API Documentation

To learn more about the methods or objects used in this guide, see the following API documentation:

• createIndex()

• Indexes object

• dropIndex()

• createSearchIndex()

• listSearchIndexes()

• updateSearchIndex()

• dropSearchIndex()