Manage computes

A compute is a virtualized service that runs applications. In Neon, a compute runs Postgres.

Each project has a primary read-write compute for its default branch. Neon supports both read-write and read replica computes. A branch can have one primary (read-write) compute and multiple read replica computes. A compute is required to connect to a Neon branch (where your database resides) from a client or application.

To connect to a database in a branch, you must use a compute associated with that branch. The following diagram illustrates how an application connects to a branch via its compute:

Project
    |---- default branch (main) ---- compute <--- application/client
             |    |
             |    |---- database
             |
             ---- child branch ---- compute <--- application/client
                            |
                            |---- database

Your Neon plan determines the resources (vCPUs and RAM) available to a compute. The Neon Free Plan supports computes with up to 2 vCPUs and 8 GB of RAM. Paid plans offer larger compute sizes. Larger computes consume more compute hours over the same period of active time than smaller computes.

View a compute

A compute is associated with a branch. To view a compute, select Branches in the Neon Console, and select a branch. If the branch has a compute, it is shown on the Computes tab on the branch page.

Compute details shown on the Computes tab include:

• The type of compute, which can be Primary (read-write) or Read Replica (read-only).
• The compute status, typically Active or Idle.
• Compute ID: The compute ID, which always starts with an ep- prefix; for example: ep-quiet-butterfly-w2qres1h
• Size: The size of the compute. Shows autoscaling minimum and maximum vCPU values if autoscaling is enabled.
• Last active: The date and time the compute was last active.

Edit, Monitor, and Connect actions for a compute can be accessed from the Computes tab.

Create a compute

You can only create a single primary read-write compute for a branch that does not have a compute, but a branch can have multiple read replica computes.

To create an endpoint:

1. In the Neon Console, select Branches.
2. Select a branch.
3. On the Computes tab, click Add a compute or Add Read Replica if you already have a primary read-write compute.
4. On the Add new compute drawer or Add read replica drawer, specify your compute settings, and click Add. Selecting the Read replica compute type creates a read replica.

Edit a compute

You can edit a compute to change the compute size or scale to zero configuration.

To edit a compute:

1. In the Neon Console, select Branches.

2. Select a branch.

3. From the Computes tab, select Edit for the compute you want to edit.

   The Edit drawer opens, letting you modify settings such as compute size, the autoscaling configuration (if applicable), and your scale to zero setting.

4. Once you've made your changes, click Save. All changes take immediate effect.

For information about selecting an appropriate compute size or autoscaling configuration, see How to size your compute.

What happens to the compute when making changes

Some key points to understand about how your endpoint responds when you make changes to your compute settings:

• Changing the size of your fixed compute restarts the endpoint and temporarily disconnects all existing connections.

  note

  When your compute resizes automatically as part of the autoscaling feature, there are no restarts or disconnects; it just scales.

• Editing minimum or maximum autoscaling sizes also requires a restart; existing connections are temporarily disconnected.
• If you disable scale to zero, you may need to restart your compute manually to get the latest compute-related release updates from Neon if updates are not applied automatically by a scheduled update. Scheduled updates are applied according to certain criteria, so not all computes receive these updates automatically. See Restart a compute.

To avoid prolonged interruptions resulting from compute restarts, we recommend configuring your clients and applications to reconnect automatically in case of a dropped connection. See Handling connection disruptions.

Compute size and autoscaling configuration

You can change compute size settings when editing a compute.

Compute size is the number of Compute Units (CUs) assigned to a Neon compute. The number of CUs determines the processing capacity of the compute. One CU has 1 vCPU and 4 GB of RAM, 2 CUs have 2 vCPUs and 8 GB of RAM, and so on. The amount of RAM in GB is always 4 times the vCPUs, as shown in the table below.

Neon supports fixed-size and autoscaling compute configurations.

• Fixed size: Select a fixed compute size ranging from .25 CUs to 56 CUs. A fixed-size compute does not scale to meet workload demand.
• Autoscaling: Specify a minimum and maximum compute size. Neon scales the compute size up and down within the selected compute size boundaries in response to the current load. Currently, the Autoscaling feature supports a range of 1/4 (.25) CU to 16 CUs. The 1/4 CU and 1/2 CU settings are shared compute. For information about how Neon implements the Autoscaling feature, see Autoscaling.

How to size your compute

The size of your compute determines the amount of frequently accessed data you can cache in memory and the maximum number of simultaneous connections you can support. As a result, if your compute size is too small, this can lead to suboptimal query performance and connection limit issues.

In Postgres, the shared_buffers setting defines the amount of data that can be held in memory. In Neon, the shared_buffers parameter scales with compute size and Neon also uses a Local File Cache (LFC) to extend the amount of memory available for caching data. The LFC can use up to 80% of your compute's RAM.

The Postgres max_connections setting defines your compute's maximum simultaneous connection limit and is set according to your compute size configuration.

The following table outlines the vCPU, RAM, LFC size (80% of RAM), and the max_connections limit for each compute size that Neon supports. To understand how max_connections is determined for an autoscaling configuration, see Parameter settings that differ by compute size.

When selecting a compute size, ideally, you want to keep as much of your dataset in memory as possible. This improves performance by reducing the amount of reads from storage. If your dataset is not too large, select a compute size that will hold the entire dataset in memory. For larger datasets that cannot be fully held in memory, select a compute size that can hold your working set. Selecting a compute size for a working set involves advanced steps, which are outlined below. See Sizing your compute based on the working set.

Regarding connection limits, you'll want a compute size that can support your anticipated maximum number of concurrent connections. If you are using Autoscaling, it is important to remember that your max_connections setting is based on both your minimum and the maximum compute size. See Parameter settings that differ by compute size for details. To avoid any max_connections constraints, you can use a pooled connection with your application, which supports up to 10,000 concurrent user connections. See Connection pooling.

Sizing your compute based on the working set

If it's not possible to hold your entire dataset in memory, the next best option is to ensure that your working set is in memory. A working set is your frequently accessed or recently used data and indexes. To determine whether your working set is fully in memory, you can query the cache hit ratio for your Neon compute. The cache hit ratio tells you how many queries are served from memory. Queries not served from memory bypass the cache to retrieve data from Neon storage (the Pageserver), which can affect query performance.

As mentioned above, Neon computes use a Local File Cache (LFC) to extend Postgres shared buffers. You can monitor the Local File Cache hit rate and your working set size from Neon's Monitoring page, where you'll find the following charts:

• Local file cache hit rate
• Working set size

Neon also provides a neon extension with a neon_stat_file_cache view that you can use to query the cache hit ratio for your compute's Local File Cache. For more information, see The neon extension.

Autoscaling considerations

Autoscaling is most effective when your data (either your full dataset or your working set) can be fully cached in memory on the minimum compute size in your autoscaling configuration.

Consider this scenario: If your data size is approximately 6 GB, starting with a compute size of .25 CU can lead to suboptimal performance because your data cannot be adequately cached. While your compute will scale up from .25 CU on demand, you may experience poor query performance until your compute scales up and fully caches your working set. You can avoid this issue if your minimum compute size can hold your working set in memory.

As mentioned above, your max_connections setting is based on both your minimum and maximum compute size settings. To avoid any max_connections constraints, you can use a pooled connection for your application. See Connection pooling.

Scale to zero configuration

Neon's Scale to Zero feature automatically transitions a compute into an idle state after 5 minutes of inactivity. You can disable scale to zero to maintain an "always-active" compute. An "always-active" configuration eliminates the few hundred milliseconds seconds of latency required to reactivate a compute but is likely to increase your compute time usage on systems where the database is not always active.

For more information, refer to Configuring scale to zero for Neon computes.

Restart a compute

It is sometimes necessary to restart a compute. Reasons for restarting a compute might include:

• Applying upgraded limits after upgrading to a paid plan
• Picking up the latest compute-related updates, which Neon typically releases weekly
• Picking up a new Postgres extension or extension version released by Neon
• Resolving performance issues or unexpected behavior

Restarting ensures your compute is running with the latest configurations and improvements.

You can restart a compute using one of the following methods:

• Issue a Restart endpoint call using the Neon API. You can do this directly from the Neon API Reference using the Try It! feature or via the command line with a cURL command similar to the one shown below. You'll need your project ID, compute endpoint ID, and an API key.

  curl --request POST \
     --url https://console.neon.tech/api/v2/projects/cool-forest-86753099/endpoints/ep-calm-flower-a5b75h79/restart \
     --header 'accept: application/json' \
     --header 'authorization: Bearer $NEON_API_KEY'

• Stop activity on your compute (stop running queries) and wait for your compute to suspend due to inactivity. By default, Neon suspends a compute after 5 minutes of inactivity. You can watch the status of your compute on the Branches page in the Neon Console. Select your branch and monitor your compute's Status field. Wait for it to report an Idle status. The compute will restart the next time it's accessed, and the status will change to Active.
• Temporarily resizing your compute or changing your autoscaling minimum or maximum compute size setting restarts a compute. For compute resize instructions, see Edit a compute.

Delete a compute

A branch can have a single read-write compute and multiple read replica computes. You can delete any of these computes from a branch. However, be aware that a compute is required to connect to a branch and access its data. If you delete a compute and add it back later, the new compute will have different connection details.

To delete a compute:

1. In the Neon Console, select Branches.
2. Select a branch.
3. On the Computes tab, click Edit for the compute you want to delete.
4. At the bottom of the Edit compute drawer, click Delete compute.

Manage computes with the Neon API

Compute actions performed in the Neon Console can also be performed using the Neon API. The following examples demonstrate how to create, view, update, and delete computes using the Neon API. For other compute-related API methods, refer to the Neon API reference.

The jq option specified in each example is an optional third-party tool that formats the JSON response, making it easier to read. For information about this utility, see jq.

Prerequisites

A Neon API request requires an API key. For information about obtaining an API key, see Create an API key. In the cURL examples below, $NEON_API_KEY is specified in place of an actual API key, which you must provide when making a Neon API request.

Create a compute with the API

The following Neon API method creates a compute.

POST /projects/{project_id}/endpoints

The API method appears as follows when specified in a cURL command. The branch you specify cannot have an existing compute. A compute must be associated with a branch. Neon supports read-write and read replica compute. A branch can have a single primary read-write compute but supports multiple read replica computes.

curl -X 'POST' \
  'https://console.neon.tech/api/v2/projects/hidden-cell-763301/endpoints' \
  -H 'accept: application/json' \
  -H "Authorization: Bearer $NEON_API_KEY" \
  -H 'Content-Type: application/json' \
  -d '{
  "endpoint": {
    "branch_id": "br-blue-tooth-671580",
    "type": "read_write"
  }
}'

{
  "endpoint": {
    "host": "ep-aged-math-668285.us-east-2.aws.neon.tech",
    "id": "ep-aged-math-668285",
    "project_id": "hidden-cell-763301",
    "branch_id": "br-blue-tooth-671580",
    "autoscaling_limit_min_cu": 1,
    "autoscaling_limit_max_cu": 1,
    "region_id": "aws-us-east-2",
    "type": "read_write",
    "current_state": "init",
    "pending_state": "active",
    "settings": {
      "pg_settings": {}
    },
    "pooler_enabled": false,
    "pooler_mode": "transaction",
    "disabled": false,
    "passwordless_access": true,
    "created_at": "2023-01-04T18:39:41Z",
    "updated_at": "2023-01-04T18:39:41Z",
    "proxy_host": "us-east-2.aws.neon.tech"
  },
  "operations": [
    {
      "id": "e0e4da91-8576-4348-913b-aaf61a46d314",
      "project_id": "hidden-cell-763301",
      "branch_id": "br-blue-tooth-671580",
      "endpoint_id": "ep-aged-math-668285",
      "action": "start_compute",
      "status": "running",
      "failures_count": 0,
      "created_at": "2023-01-04T18:39:41Z",
      "updated_at": "2023-01-04T18:39:41Z"
    }
  ]
}

List computes with the API

The following Neon API method lists computes for the specified project. A compute belongs to a Neon project. To view the API documentation for this method, refer to the Neon API reference.

GET /projects/{project_id}/endpoints

The API method appears as follows when specified in a cURL command:

curl -X 'GET' \
  'https://console.neon.tech/api/v2/projects/hidden-cell-763301/endpoints' \
  -H 'accept: application/json' \
  -H "Authorization: Bearer $NEON_API_KEY"

{
  "endpoints": [
    {
      "host": "ep-young-art-646685.us-east-2.aws.neon.tech",
      "id": "ep-young-art-646685",
      "project_id": "hidden-cell-763301",
      "branch_id": "br-shy-credit-899131",
      "autoscaling_limit_min_cu": 1,
      "autoscaling_limit_max_cu": 1,
      "region_id": "aws-us-east-2",
      "type": "read_write",
      "current_state": "idle",
      "settings": {
        "pg_settings": {}
      },
      "pooler_enabled": false,
      "pooler_mode": "transaction",
      "disabled": false,
      "passwordless_access": true,
      "last_active": "2023-01-04T18:38:25Z",
      "created_at": "2023-01-04T18:38:23Z",
      "updated_at": "2023-01-04T18:43:36Z",
      "proxy_host": "us-east-2.aws.neon.tech"
    },
    {
      "host": "ep-aged-math-668285.us-east-2.aws.neon.tech",
      "id": "ep-aged-math-668285",
      "project_id": "hidden-cell-763301",
      "branch_id": "br-blue-tooth-671580",
      "autoscaling_limit_min_cu": 1,
      "autoscaling_limit_max_cu": 1,
      "region_id": "aws-us-east-2",
      "type": "read_write",
      "current_state": "idle",
      "settings": {
        "pg_settings": {}
      },
      "pooler_enabled": false,
      "pooler_mode": "transaction",
      "disabled": false,
      "passwordless_access": true,
      "last_active": "2023-01-04T18:39:42Z",
      "created_at": "2023-01-04T18:39:41Z",
      "updated_at": "2023-01-04T18:44:48Z",
      "proxy_host": "us-east-2.aws.neon.tech"
    }
  ]
}

Update a compute with the API

The following Neon API method updates the specified compute. To view the API documentation for this method, refer to the Neon API reference.

PATCH /projects/{project_id}/endpoints/{endpoint_id}

The API method appears as follows when specified in a cURL command. The example reassigns the compute to another branch by changing the branch_id. The branch that you specify cannot have an existing compute. A compute must be associated with a branch, and a branch can have only one primary read-write compute. Multiple read-replica computes are allowed.

curl -X 'PATCH' \
  'https://console.neon.tech/api/v2/projects/hidden-cell-763301/endpoints/ep-young-art-646685' \
  -H 'accept: application/json' \
  -H "Authorization: Bearer $NEON_API_KEY" \
  -H 'Content-Type: application/json' \
  -d '{
  "endpoint": {
    "branch_id": "br-green-lab-617946"
  }
}'

{
  "endpoint": {
    "host": "ep-young-art-646685.us-east-2.aws.neon.tech",
    "id": "ep-young-art-646685",
    "project_id": "hidden-cell-763301",
    "branch_id": "br-green-lab-617946",
    "autoscaling_limit_min_cu": 1,
    "autoscaling_limit_max_cu": 1,
    "region_id": "aws-us-east-2",
    "type": "read_write",
    "current_state": "idle",
    "pending_state": "idle",
    "settings": {
      "pg_settings": {}
    },
    "pooler_enabled": false,
    "pooler_mode": "transaction",
    "disabled": false,
    "passwordless_access": true,
    "last_active": "2023-01-04T18:38:25Z",
    "created_at": "2023-01-04T18:38:23Z",
    "updated_at": "2023-01-04T18:47:36Z",
    "proxy_host": "us-east-2.aws.neon.tech"
  },
  "operations": [
    {
      "id": "03bf0bbc-cc46-4863-a5c4-f31fc1881228",
      "project_id": "hidden-cell-763301",
      "branch_id": "br-green-lab-617946",
      "endpoint_id": "ep-young-art-646685",
      "action": "apply_config",
      "status": "running",
      "failures_count": 0,
      "created_at": "2023-01-04T18:47:36Z",
      "updated_at": "2023-01-04T18:47:36Z"
    },
    {
      "id": "c96be00c-6340-4fb2-b80a-5ae96f469969",
      "project_id": "hidden-cell-763301",
      "branch_id": "br-green-lab-617946",
      "endpoint_id": "ep-young-art-646685",
      "action": "suspend_compute",
      "status": "scheduling",
      "failures_count": 0,
      "created_at": "2023-01-04T18:47:36Z",
      "updated_at": "2023-01-04T18:47:36Z"
    }
  ]
}

Delete a compute with the API

The following Neon API method deletes the specified compute. To view the API documentation for this method, refer to the Neon API reference.

DELETE /projects/{project_id}/endpoints/{endpoint_id}

The API method appears as follows when specified in a cURL command.

curl -X 'DELETE' \
  'https://console.neon.tech/api/v2/projects/hidden-cell-763301/endpoints/ep-young-art-646685' \
  -H 'accept: application/json' \
  -H "Authorization: Bearer $NEON_API_KEY"

{
  "endpoint": {
    "host": "ep-young-art-646685.us-east-2.aws.neon.tech",
    "id": "ep-young-art-646685",
    "project_id": "hidden-cell-763301",
    "branch_id": "br-green-lab-617946",
    "autoscaling_limit_min_cu": 1,
    "autoscaling_limit_max_cu": 1,
    "region_id": "aws-us-east-2",
    "type": "read_write",
    "current_state": "idle",
    "settings": {
      "pg_settings": {}
    },
    "pooler_enabled": false,
    "pooler_mode": "transaction",
    "disabled": false,
    "passwordless_access": true,
    "last_active": "2023-01-04T18:38:25Z",
    "created_at": "2023-01-04T18:38:23Z",
    "updated_at": "2023-01-04T18:47:45Z",
    "proxy_host": "us-east-2.aws.neon.tech"
  },
  "operations": []
}

Compute-related issues

This section outlines compute-related issues you may encounter and possible resolutions.

No space left on device

You may encounter an error similar to the following when your compute's local disk storage is full:

ERROR: could not write to file "base/pgsql_tmp/pgsql_tmp1234.56.fileset/o12of34.p1.0": No space left on device (SQLSTATE 53100)

Neon computes allocate 20 GiB of local disk space or 15 GiB x the maximum compute size (whichever is highest) for temporary files used by Postgres. Data-intensive operations can sometimes consume all of this space, resulting in No space left on device errors.

To resolve this issue, you can try the following strategies:

• Identify and terminate resource-intensive processes: These could be long-running queries, operations, or possibly sync or replication activities. You can start your investigation by listing running queries by duration.
• Optimize queries to reduce temporary file usage.
• Adjust pipeline settings for third-party sync or replication: If you're syncing or replicating data with an external service, modify the pipeline settings to control disk space usage.

If the issue persists, refer to our Neon Support channels.

Compute is not suspending

In some cases, you may observe that your compute remains constantly active for no apparent reason. Possible causes for a constantly active compute when not expected include:

• Connection requests: Frequent connection requests from clients, applications, or integrations can prevent a compute from suspending automatically. Each connection resets the scale to zero timer.
• Background processes: Some applications or background jobs may run periodic tasks that keep the connection active.

Possible steps you can take to identify the issues include:

1. Checking for active processes

   You can run the following query to identify active sessions and their states:

   SELECT
     pid,
     usename,
     query,
     state,
     query_start
   FROM
     pg_stat_activity
   WHERE
     query_start >= now() - interval '24 hours'
   ORDER BY
     query_start DESC;

   Look for processes initiated by your users, applications, or integrations that may be keeping your compute active.

2. Review connection patterns

   • Ensure that no applications are sending frequent, unnecessary connection requests.
   • Consider batching connections if possible, or use connection pooling to limit persistent connections.

3. Optimize any background jobs

   If background jobs are needed, reduce their frequency or adjust their timing to allow Neon's scale to zero feature to activate after the defined period of inactivity (the default is 5 minutes). For more information, refer to our Scale to zero guide.