Use MongoDB Views to Transform Documents and Filter Collections for Atlas Search

Requirements

You must use:

• MongoDB 8.0 or higher.

During the Preview period, you must use:

• mongosh or Compass to create and manage MongoDB Views.

• Atlas UI and the Atlas Administration API to create Atlas Search indexes on Views. Support for mongosh, Compass, and Drivers will be available when this feature is Generally Available.

To edit a View, you must have a User Admin role and use the collMod database command.

Limitations

• Atlas Search supports Views only for $expr in the following stages:

  • $addFields

  • $set

  • $match

• Index names must be unique across a source collection and all of its Views.

• Atlas Search doesn't support View definitions with variables that produce dynamic results like $$USER_ROLES and $random.

• Atlas Search queries return the original documents as they appear in the source collection.

Example: Filter Documents

To create a View, you must have the createCollection privilege.

You can partially index a collection to filter documents. The following example creates a View on the sample_mflix.movies collection so that you can search for only movies released after January 1, 2000.

use sample_mflix

db.createView(
  "movies_ReleasedAfter2000",
  "movies",
  [
    {
      $match: {
        $expr: {
          $gt: [
            "$released",
            ISODate("2000-01-01")
          ]
        }
      }
    }
  ]
)

use sample_mflix

1
db.movies.aggregate([
2
  {
3
    $search: {
4
      index: "releasedAfter2000Index",
5
      text: {
6
        path: "title",
7
        query: "foo"
8
      },
9
      sort: {
10
        released: 1
11
      }
12
    }
13
  }
14
])

[
  {
    _id: ObjectId('573a13d2f29313caabd929f8'),
    plot: "Rising from the ashes of Nirvana, the Foo Fighters became a Grammy-winning sensation on their own. Sixteen years of the band's history comes to life in this documentary, from their demo ...",
    genres: [ 'Documentary', 'Music' ],
    runtime: 150,
    cast: [
      'Shawn Cloninger',
      'William Goldsmith',
      'Jessy Greene',
      'Dave Grohl'
    ],
    num_mflix_comments: 0,
    poster: 'https://m.media-amazon.com/images/M/MV5BMzE4OTczMTgxM15BMl5BanBnXkFtZTcwNTU1NjQxOA@@._V1_SY1000_SX677_AL_.jpg',
    title: 'Foo Fighters: Back and Forth',
    fullplot: `Rising from the ashes of Nirvana, the Foo Fighters became a Grammy-winning sensation on their own. Sixteen years of the band's history comes to life in this documentary, from their demo tapes through the creation of their 2011 album, "Wasting Light."`,
    languages: [ 'English' ],
    released: ISODate('2011-04-05T00:00:00.000Z'),
    directors: [ 'James Moll' ],
    awards: { wins: 1, nominations: 1, text: '1 win & 1 nomination.' },
    lastupdated: '2015-08-19 00:00:25.937000000',
    year: 2011,
    imdb: { rating: 8.4, votes: 3745, id: 1853563 },
    countries: [ 'USA' ],
    type: 'movie',
    tomatoes: {
      viewer: { rating: 4.4, numReviews: 857, meter: 96 },
      dvd: ISODate('2011-08-08T00:00:00.000Z'),
      website: 'http://us.foofightersfilm.com/',
      production: 'Cinedigm Digital Cinema',
      lastUpdated: ISODate('2015-09-12T18:42:01.000Z')
    }
  }
]

Example: Add or Modify Fields

The following example lets you search the sample_airbnb.listingsAndReviews collection for accomodatations based on a new totalPrice field, which is the sum of the price and cleaningFee fields. Also, since Atlas Search doesn't support Decimal128 types, we transform the values to Double.

use sample_airbnb

db.createView(
  "listingsAndReviews_totalPrice",
  "listingsAndReviews",
  [
    {
      $addFields: {
        totalPrice: {
          $add: [
            {
              $ifNull: [{ $toDouble: "$price" }, 0]
            },
            {
              $ifNull: [{ $toDouble: "$cleaning_fee" }, 0]
            }
          ]
        }
      }
    }
  ]
)

use sample_airbnb

1
db.listingsAndReviews.aggregate([
2
  {
3
    $search: {
4
      index: "totalPriceIndex",
5
      range: {
6
        path: "totalPrice",
7
        lte: 300
8
      },
9
      returnStoredSource: true
10
    }
11
  }
12
])

[
  { _id: '10006546', totalPrice: 115 },
  { _id: '1001265', totalPrice: 215 },
  { _id: '10021707', totalPrice: 40 },
  { _id: '1003530', totalPrice: 270 },
  { _id: '10038496', totalPrice: 269 },
  { _id: '10051164', totalPrice: 250 },
  { _id: '10057447', totalPrice: 50 },
  { _id: '10057826', totalPrice: 205 },
  { _id: '10059244', totalPrice: 43 },
  { _id: '10066928', totalPrice: 140 },
  { _id: '10082422', totalPrice: 60 },
  { _id: '10083468', totalPrice: 40 },
  { _id: '10084023', totalPrice: 231 },
  { _id: '10091713', totalPrice: 231 },
  { _id: '10092679', totalPrice: 58 },
  { _id: '10096773', totalPrice: 205 },
  { _id: '10112159', totalPrice: 90 },
  { _id: '10117617', totalPrice: 55 },
  { _id: '10120414', totalPrice: 150 },
  { _id: '10133554', totalPrice: 121 }
]

Edit a View

The following example updates the movies_ReleasedAfter2000 MongoDB View for movies before 2000.

db.runCommand(
{
    collMod: "movies_ReleasedAfter2000",
    viewOn: "movies",
    "pipeline": [
      {
        $match: {
          $expr: {
            $lt: [
              "$released",
              ISODate("2000-01-01T00")
            ]
          }
        }
      }
    ]
  }
)

After you run this command, Atlas Search automatically detects the change in the View definition and performs a reindexing with no downtime.

Return the Pipelines for a View

The following example returns the pipelines on the movies_ReleasedAfter2000 View.

1
db.getCollectionInfos({ name: "movies_ReleasedAfter2000" })[0].options.pipeline

[
  {
    '$match': {
      '$expr': { '$gt': [ '$released', ISODate('2000-01-01T00:00:00.000Z') ] }
    }
  }
]

Troubleshoot

Indexes change to the FAILED status in the following scenarios:

• You create an index on a View that is incompatible with Atlas Search.

• You edit a View in a way that does not meet the Atlas Search compatibility requirements.

• You remove or change a View's source collection.

  For example, if one View is created on another View, and you change the parent View source to another collection.

  Note

  This limitation also applies if a View is a descendent of other Views. For example, you can't change or remove the source collection that all descendents originate from.

Indexes stall in the following scenarios:

• If the View definition causes an aggregation failure while an index is READY, the index becomes STALE. The index will return to READY after you resolve the document or change the view definition so that it doesn't fail anymore. However, the index is queryable until the replication is automatically removed from the oplog.

• If the View definition causes an aggregation pipeline failure while the index is BUILDING, the index build is stuck until you fix the document. The index will return to READY after you resolve the document or change the view definition so that it doesn't fail anymore.

You can view index statuses in the Atlas UI on the index status details page.

Index Process

When you create an Atlas Search index on a View, the mongot process performs the same tasks as when you create an Atlas Search index on a regular collection. The mongot process:

1. Creates Atlas Search indexes based on the rules in the index definition for the collection.

2. Monitors change streams for the current state of the documents and indexes for the collections for which you defined the Atlas Search indexes.

3. Processes Atlas Search queries and returns the document IDs and other search metadata for the matching documents to mongod, which then does a full document lookup and returns the results to the client.

When you create an Atlas Search index on a View, the View definition is applied during Step 1 and 2, and the transformed documents are stored in the Atlas Search index on disk.

Learn More

To learn more about Views, see Views.

To create an Atlas Vector Search index on a View, see Use MongoDB Views to Transform Documents and Filter Collections for Atlas Vector Search.