Deploy a Federated Database Instance

1. Select the dataset for your federated database instance from the Data Sources section.

   Click Add Data Sources to select your data store.

2. Specify your data source.

   1. Choose Atlas Cluster to configure a federated database instance for data on your Atlas cluster.

      Corresponds to stores.[n].provider JSON configuration setting.

   2. Select the Atlas cluster that you want to use as a data store in the Provide Namespaces in this project section.

      Corresponds to stores.[n].clusterName JSON configuration setting.

   3. Expand the databases and select the collections that you want to add to your federated database instance.

      To filter the databases and collections, enter text into the Search database or collection field. The dialog box displays only databases and collections with names that match your search criteria.

      Corresponds to the databases.[n].collections.[n].dataSources.[n].database and databases.[n].collections.[n].dataSources.[n].collection JSON configuration settings.

   4. Optional. Specify the Cluster Read Preference settings by expanding the section.

      Corresponds to stores.[n].readPreference.

      Field Name	Description
      Read Preference Mode	Specifies the replica set member to which you want to route the read requests. You can choose one of the following from the dropdown: primary - to route all read requests to the replica set primary primaryPreferred - to route all read requests the replica set primary and to secondary members only if primary is unavailable secondary - to route all read requests to the secondary members of the replica set secondaryPreferred - to route all read requests to the secondary members of the replica set and the primary on sharded clusters only if secondary members are unavailable nearest - to route all read requests to random eligible replica set member, irrespective of whether that member is a primary or secondary If you add an Atlas cluster as a store, the value default value is secondary. If you don't set anything in your federated database instance storage configuration, the default value is nearest. To learn more, see Read preference mode. Corresponds to stores.[n].readPreference.mode.
      TagSets	Specifies the list of tags or tag specification documents that contain name and value pairs for the replica set member to which you want to route read requests. To learn more, see Read Preference Tag Sets. Corresponds to stores.[n].readPreference.tagSets.
      Maxstaleness Seconds	Specifies the maximum replication lag, or "staleness", for reads from secondaries. To learn more, see Read Preference maxStalenessSeconds. Corresponds to stores.[n].readPreference.maxStalenessSeconds.

   5. Click Next.

3. Create the virtual databases, collections, and views and map the databases, collections, and views to your data store.

   1. (Optional) Click the for the:

      • Database to edit the database name. Defaults to VirtualDatabase[n].

        Corresponds to databases.[n].name JSON configuration setting.

      • Collection to edit the collection name. Defaults to VirtualCollection[n].

        Corresponds to databases.[n].collections.[n].name JSON configuration setting.

      • View to edit the view name.

      You can click:

      • Add Database to add databases and collections.

      • associated with the database to add collections to the database.

      • associated with the collection to add views on the collection. To create a view, you must specify:

        • The name of the view.

        • The pipeline to apply to the view.

          The view definition pipeline cannot include the $out or the $merge stage. If the view definition includes nested pipeline stages such as $lookup or $facet, this restriction applies to those nested pipelines as well.

        To learn more about views, see:

        • Views

        • db.createView

      • associated with the database, collection, or view to remove it.

   2. Select Atlas Cluster from the dropdown in the Data Sources section.

   3. Drag and drop the data store to map with the collection.

      Corresponds to databases.[n].collections.[n].dataSources JSON configuration setting.

Your configuration for an Atlas cluster data store should look similar to the following:

1
{
2
  "stores" : [
3
    {
4
      "name" : "<string>",
5
      "provider": "<string>",
6
      "clusterName": "<string>", 
7
      "projectId": "<string>",
8
      "readPreference": {
9
        "mode": "<string>",
10
        "tagSets": [
11
          [{"name": "<string>", "value": "<string>"},...],
12
          ...
13
        ],
14
        "maxStalenessSeconds": <int>
15
      }
16
    }
17
  ],
18
  "databases" : [
19
    {
20
      "name" : "<string>",
21
      "collections" : [
22
        {
23
          "name" : "<string>",
24
          "dataSources" : [
25
            {
26
              "storeName" : "<string>",
27
              "database" : "<string>",
28
              "databaseRegex": "<string>",
29
              "collection" : "<string>",
30
              "collectionRegex" : "<string>",
31
              "provenanceFieldName": "<string>"
32
            }
33
          ]
34
        }
35
      ],
36
      "views" : [ 
37
        {
38
          "name" : "<string>", 
39
          "source" : "<string>", 
40
          "pipeline" : "<string>" 
41
        }
42
      ] 
43
    }
44
  ]
45
}

To learn more about these configuration settings, see Define Data Stores for a Federated Database Instance.

1. Define your Atlas data store.

   Edit the JSON configuration settings shown in the UI for stores. Your stores cofiguration setting should resemble the following:

   "stores" : [
     {
       "name" : "<string>",
       "provider" : "<string>",
       "clusterName" : "<string>",
       "projectId": "<string>"
       "readPreference": {
         "mode": "<string>",
         "tagSets": [
           [{"name": "<string>", "value": "<string>"},...],
           ...
         ],
         "maxStalenessSeconds": <int>
       },
       "readConcern": {
         "level": "<string>"
       }
     }
   ]

   To learn more about these configuration settings, see stores.

2. Define your federated database instance virtual databases, collections, and views.

   Edit the JSON configuration settings shown in the UI for databases. Your databases cofiguration setting should resemble the following:

   "databases" : [
     {
       "name" : "<string>",
       "collections" : [
         {
           "name" : "<string>",
           "dataSources" : [
             {
               "storeName" : "<string>",
               "database" : "<string>",
               "databaseRegex": "<string>",
               "collection" : "<string>",
               "collectionRegex" : "<string>",
               "provenanceFieldName": "<string>" 
             }
           ]
         }
       ]
     }
   ]

   To learn more about these configuration settings, see databases.