Summary: Neon read replica management guide covering how to add a read-only compute to any branch, connect to it, and adjust its size or Scale to Zero settings via the Console, CLI, or API. Use this page when you need step-by-step instructions for offloading read traffic (analytics, horizontal scaling, read-only access) to a separate compute endpoint on an existing Neon branch. Available on all Neon plans. Includes replication delay monitoring and automatic synchronization of max_connections and related Postgres parameters between primary and replica computes.

Learn how to create and manage read replicas in Neon

Read replicas are supported with all Neon plans. The Free plan is limited to a maximum of 3 read replica computes per project. This guide steps you through the process of creating and managing read replicas.

The general purpose of read replicas is to segregate read-only work from your production database operations. This can be applied to different uses cases, such as:

• Horizontal scaling: Distributing read requests across replicas to improve performance and increase throughput
• Analytics queries: Offloading resource-intensive analytics and reporting workloads to reduce load on the primary compute
• Read-only access: Granting read-only access to users or applications that don't require write permissions

Regardless of the application, the steps for creating, configuring, and connecting to a read replica are the same. You can create one or more read replicas for any branch in your Neon project and configure the compute size allocated to each. Neon's Autoscaling and Scale to Zero features are also supported, providing you with control over read replica compute usage.

• A Neon account
• A Neon project

Creating a read replica involves adding a read replica compute to a branch. You can add a read replica compute to any branch in your Neon project using the Neon Console, Neon CLI, or Neon API.

Note: The Free plan is limited to a maximum of 3 read replica computes per project.

Console

To create a read replica from the Neon Console:

1. In the Neon Console, select your branch from the project/branch menu at the top of the sidebar.

2. Under Postgres database, select Computes.

3. Click Add Read Replica.

4. On the Add new compute dialog, select Read replica as the Compute type.

5. Specify the Compute size settings. You can configure a Fixed Size compute with a specific amount of RAM (the default) or enable autoscaling by configuring a minimum and maximum compute size. You can also configure the Suspend compute after inactivity setting, which is the amount of idle time after which your compute is automatically suspended. The default setting is 5 minutes.

   Note: The compute size configuration determines the processing power of your database.

6. When you finish making your selections, click Create.

In a few seconds, your read replica is provisioned and appears on the Computes tab under Postgres database. The following section describes how to connect to your read replica.

CLI

To create a read replica using the Neon CLI, use the branches command, specifying the add-compute subcommand with --type read_only. If you have more than one Neon project, also include the --project-id option.

neon branches add-compute mybranch --type read_only

API

To create a read replica compute using the Neon API, use the Create endpoint method. The type attribute in the following example specifies read_only, which creates a read replica compute. For information about obtaining the required project_id and branch_id parameters, refer to Create an endpoint, in the Neon API Reference.

curl --request POST \
     --url https://console.neon.tech/api/v2/projects/<project_id>/endpoints \
     --header 'Accept: application/json' \
     --header "Authorization: Bearer $NEON_API_KEY" \
     --header 'Content-Type: application/json' \
     --data '
{
  "endpoint": {
    "type": "read_only",
    "branch_id": "<branch_id>"
  }
}
' | jq

Connecting to a read replica is the same as connecting to any branch, except you connect via a read replica compute instead of your primary read-write compute. The following steps describe how to connect to your read replica with connection details obtained from the Neon Console.

1. Click the Connect button in the Console nav. On the Connect to your branch modal, select the branch, the database, and the role you want to connect with.

2. Under Compute, select a Replica.

3. Select a connection string or a code example from the drop-down menu and copy it. This is the information you need to connect to the read replica from your client or application.

   A psql connection string appears similar to the following:

   postgresql://[user]:[password]@[neon_hostname]/[dbname]?sslmode=require&channel_binding=require

   If you expect a high number of connections, enable the Connection pooling toggle to add the -pooler flag to the connection string or example.

   Note: Write operations are not permitted on a read replica connection.

You can view read replicas using the Neon Console or Neon API.

Console

To view read replicas for a branch, in the Neon Console select your branch from the project/branch menu at the top of the sidebar, then select Postgres database > Computes. Read replicas are listed on the Computes tab.

API

To view read replica computes with the Neon API, use the Get endpoints method.

curl -X 'GET' \
  'https://console.neon.tech/api/v2/projects/<project_id>/endpoints' \
  -H 'accept: application/json' \
  -H "Authorization: Bearer $NEON_API_KEY"

For information about obtaining the required project_id parameter for this command, refer to Get endpoints, in the Neon API Reference. For information about obtaining a Neon API key, see Create an API key.

In the response body for this method, read replica computes are identified by the type value, which is read_only.

You can edit a read replica using the Neon Console or Neon API to change the Compute size or Scale to Zero configuration.

Console

To edit a read replica compute using the Neon Console:

1. In the Neon Console, select your branch from the project/branch menu at the top of the sidebar.
2. Under Postgres database, select Computes.
3. Identify the read replica compute you want to modify, and click Edit.
4. Make the changes to your compute settings, and click Save.

API

To edit a read replica compute with the Neon API, use the Update endpoint method.

curl --request PATCH \
     --url https://console.neon.tech/api/v2/projects/<project_id>/endpoints/<endpoint_id> \
     --header 'Accept: application/json' \
     --header "Authorization: Bearer $NEON_API_KEY" \
     --header 'Content-Type: application/json' \
     --data '
{
  "endpoint": {
    "autoscaling_limit_min_cu": 25,
    "autoscaling_limit_max_cu": 3,
    "suspend_timeout_seconds": 604800,
    "provisioner": "k8s-neonvm"
  }
}
'

Computes are identified by their project_id and endpoint_id. For information about obtaining the required project_id and endpoint_id parameters, refer to Update endpoint, in the Neon API Reference. For information about obtaining a Neon API key, see Create an API key.

You can delete a read replica using the Neon Console or Neon API. Deleting a read replica is a permanent action, but you can quickly create a new read replica if you need one.

Console

To delete a read replica using the Neon Console:

1. In the Neon Console, select your branch from the project/branch menu at the top of the sidebar.
2. Under Postgres database, select Computes.
3. Find the read replica you want to delete.
4. Click Edit → Delete.

API

To delete a read replica compute with the Neon API, use the Delete endpoint method.

curl --request DELETE \
     --url https://console.neon.tech/api/v2/projects/<project_id>/endpoints/<endpoint_id> \
     --header 'Accept: application/json' \
     --header "Authorization: Bearer $NEON_API_KEY"

Computes are identified by their project_id and endpoint_id. For information about obtaining the required project_id and endpoint_id parameters, refer to Delete endpoint, in the Neon API Reference. For information about obtaining a Neon API key, see Create an API key.

You can monitor replication delay between the primary compute and your read replica computes from the Monitoring page in the Neon Console. Two graphs are provided:

Replication delay bytes

The Replication delay bytes graph shows the total size, in bytes, of the data that has been sent from the primary compute but has not yet been applied on the replica. A larger value indicates a higher backlog of data waiting to be replicated, which may suggest issues with replication throughput or resource availability on the replica. This graph is only visible when selecting a Replica compute from the Compute drop-down menu.

Replication delay seconds

The Replication delay seconds graph shows the time delay, in seconds, between the last transaction committed on the primary compute and the application of that transaction on the replica. A higher value suggests that the replica is behind the primary, potentially due to network latency, high replication load, or resource constraints on the replica. This graph is only visible when selecting a Replica compute from the Compute drop-down menu.

For Neon read replicas, certain Postgres settings should not have lower values than your primary read-write compute. For this reason, the following settings on read replica computes are synchronized with the settings on the primary read-write compute when the read replica compute is started:

• max_connections
• max_prepared_transactions
• max_locks_per_transaction
• max_wal_senders
• max_worker_processes

No users action is required. The settings are synchronized automatically when you create a read replica. However, if you change the compute size configuration on the primary read-write compute, you will need to restart your read replica computes to ensure that settings remain synchronized, as described in the next section.

If your read replicas are falling behind, follow these steps to diagnose and resolve the issue:

1. Check your replication lag metrics
   Refer to Monitoring Read Replicas for instructions on how to monitor replication lag.

2. Verify configuration alignment
   If replication lag is detected, ensure that the configurations for the primary and read-replica computes are aligned. Specifically, confirm that the following parameters match between your primary compute and read-replica compute:

   • max_connections
   • max_prepared_transactions
   • max_locks_per_transaction
   • max_wal_senders
   • max_worker_processes

3. Restart read-replica computes if configurations are misaligned
   If the configurations are not aligned, restart your read-replica computes to automatically update their settings. For instructions, see Restart a Compute.

   Tip: When increasing the size of your primary read-write compute, always restart associated read replicas to ensure their configurations remain aligned.

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