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Atlas App Services

Read Preference

On this page

  • Overview
  • When To Specify Read Preference
  • Procedure
  • Navigate to the Cluster Configuration Screen
  • Specify a Cluster Read Preference
  • Specify Read Preference Tags
  • Save the Cluster Configuration
  • Pull the Latest Version of Your App
  • Specify a Cluster Read Preference
  • Specify Read Preference Tags
  • Deploy the Updated Data Source Configuration

You can configure the read preference for a linked MongoDB Atlas cluster to control the type of replica set member that Atlas App Services routes database read requests to. You can also specify a tag set to target specific members of the replica set.

You cannot set the read preference on a Federated data source.

By default, App Services uses a read preference of primary, which routes all read requests through the primary node of a replica set.

The default read preference (primary) should be sufficient for most use cases. Consider specifying a cluster read preference when you need to do the following:

  • Read from a specific secondary that has a custom configuration, such as an analytics node with special indexes optimized for reporting workloads.

  • Read from a node in a specific region of a globally distributed replica set.

  • Maintain read availability during a replica set failover, i.e., continue to read potentially stale data when there is no primary node.

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