Create and manage read pools

This page describes how to create and manage read pools for your large read workloads.

Before you begin

  1. Read pools contain copies of a primary instance. If you haven't done so already, create a Cloud SQL Enterprise Plus edition primary instance . While read pools support public IP connectivity, for the purpose of this guide, create a primary instance with private IP (PSA) connectivity. For more information about primary instances and replication, see About replication in Cloud SQL .
  2. After the primary instance is created, choose a password for the root user and run the following command to set the password on the primary instance. Save this password to use later when connecting to the read pool.
  3.   
    gcloud  
    --project = 
     PROJECT 
      
     \ 
      
    sql  
    users  
    set-password  
    root  
    --host = 
    %  
     \ 
      
    --instance = 
     PRIMARY_INSTANCE_NAME 
      
    --prompt-for-password  
    

    Make the following replacements:

    • PROJECT : the name of the project where you want the primary instance and read pool to reside.
    • PRIMARY_INSTANCE_NAME : the name of the primary instance.

Create a read pool

gcloud

For information about installing and getting started with the gcloud CLI, see Install the gcloud CLI . For information about starting Cloud Shell, see Use Cloud Shell .

Use the following gcloud sql instances create command to create a read pool with multiple read pool nodes:

  
gcloud  
sql  
instances  
create  
 READ_POOL_NAME 
  
 \ 
  
--tier = 
 TIER 
  
--edition = 
ENTERPRISE_PLUS  
 \ 
  
--instance-type = 
READ_POOL_INSTANCE  
--node-count = 
 NODE_COUNT 
  
 \ 
  
--master-instance-name = 
 PRIMARY_INSTANCE_NAME 
  

Make the following replacements:

  • READ_POOL_NAME : the name you want to use for the read pool.
  • TIER : the machine type you want to use for each read pool node in the read pool, such as db-perf-optimized-N-4 .
  • NODE_COUNT : the number of read pool nodes you want in the read pool. Choose any number from 1 to 20 .
  • PRIMARY_INSTANCE_NAME : the name of the primary instance associated with the read pool, such as my-primary-instance .

Terraform

To create a read pool, use a Terraform resource . Then, set the instance_type attribute to "READ_POOL_INSTANCE" and the node_count attribute to the number of nodes you want to use.

The following example includes resources for the primary instance and the read pool.

 resource "google_sql_database_instance" "primary" {
  name             = "mysql-primary"
  database_version = "MYSQL_8_4"
  region           = "europe-west4"

  instance_type = "CLOUD_SQL_INSTANCE"

  settings {
    tier    = "db-perf-optimized-N-2"
    edition = "ENTERPRISE_PLUS"

    backup_configuration {
      enabled            = true
      binary_log_enabled = true
    }

    ip_configuration {
      ipv4_enabled = true
    }
  }
}

resource "google_sql_database_instance" "replica" {
  name             = "mysql-replica"
  database_version = "MYSQL_8_4"
  region           = "europe-west4"

  master_instance_name = google_sql_database_instance.primary.name
  instance_type        = "READ_POOL_INSTANCE"
  node_count           = 2

  settings {
    tier    = "db-perf-optimized-N-2"
    edition = "ENTERPRISE_PLUS"

    ip_configuration {
      ipv4_enabled = true
    }
  }
} 

Apply the changes

To apply your Terraform configuration in a Google Cloud project, complete the steps in the following sections.

Prepare Cloud Shell

  1. Launch Cloud Shell .
  2. Set the default Google Cloud project where you want to apply your Terraform configurations.

    You only need to run this command once per project, and you can run it in any directory.

    export GOOGLE_CLOUD_PROJECT= PROJECT_ID 
    

    Environment variables are overridden if you set explicit values in the Terraform configuration file.

Prepare the directory

Each Terraform configuration file must have its own directory (also called a root module ).

  1. In Cloud Shell , create a directory and a new file within that directory. The filename must have the .tf extension—for example main.tf . In this tutorial, the file is referred to as main.tf .
    mkdir DIRECTORY 
    && cd DIRECTORY 
    && touch main.tf
  2. If you are following a tutorial, you can copy the sample code in each section or step.

    Copy the sample code into the newly created main.tf .

    Optionally, copy the code from GitHub. This is recommended when the Terraform snippet is part of an end-to-end solution.

  3. Review and modify the sample parameters to apply to your environment.
  4. Save your changes.
  5. Initialize Terraform. You only need to do this once per directory.
    terraform init

    Optionally, to use the latest Google provider version, include the -upgrade option:

    terraform init -upgrade

Apply the changes

  1. Review the configuration and verify that the resources that Terraform is going to create or update match your expectations:
    terraform plan

    Make corrections to the configuration as necessary.

  2. Apply the Terraform configuration by running the following command and entering yes at the prompt:
    terraform apply

    Wait until Terraform displays the "Apply complete!" message.

  3. Open your Google Cloud project to view the results. In the Google Cloud console, navigate to your resources in the UI to make sure that Terraform has created or updated them.

Delete the changes

To delete your changes, do the following:

  1. To disable deletion protection, in your Terraform configuration file set the deletion_protection argument to false .
    deletion_protection =  "false"
  2. Apply the updated Terraform configuration by running the following command and entering yes at the prompt:
    terraform apply
  1. Remove resources previously applied with your Terraform configuration by running the following command and entering yes at the prompt:

    terraform destroy

REST v1

Use the insert method of the instances resource to create a read pool with multiple read pool nodes. The databaseVersion property must be the same as the primary.

Before using any of the request data, make the following replacements:

  • PROJECT : the name of the project where you want the primary instance and read pool to reside.
  • REGION : the region for the read pool, such as us-east1 . The region must be the same as the primary instance.
  • TIER : the machine type you want to use for each read pool node in the read pool, such as db-perf-optimized-N-4 .
  • PRIMARY_INSTANCE_NAME : the name of the primary instance.
  • READ_POOL_NAME : the name you want to use for the read pool, such as my-read-pool .
  • DATABASE_VERSION : the database version you want to use. For example, MYSQL_8_0_37 .
  • NODE_COUNT : the number of read pool nodes you want in the read pool. Choose any number from 1 to 20 .
  • FULL_NETWORK_NAME : the full network path where you want the read pool to reside, such as projects/vpc-host-project/global/networks/my-network-name .

HTTP method and URL:

POST https://sqladmin.googleapis.com/v1/projects/ PROJECT 
/instances

Request JSON body:

{
  "name": " READ_POOL_NAME 
",
  "masterInstanceName": " PRIMARY_INSTANCE_NAME 
",
  "project": " PROJECT 
",
  "databaseVersion": " DATABASE_VERSION 
",
  "region": " REGION 
",
  "instanceType": "READ_POOL_INSTANCE",
  "nodeCount": NODE_COUNT 
,
  "settings": {
    "tier": " TIER 
",
    "edition": "ENTERPRISE_PLUS",
    "ipConfiguration": {
      "ipv4Enabled": false,
      "privateNetwork": " FULL_NETWORK_NAME 
"
    }
  }
}

To send your request, expand one of these options:

You should receive a JSON response similar to the following:

REST v1beta4

Use the insert method of the instances resource to create a read pool with multiple read pool nodes. The databaseVersion property must be the same as the primary.

Before using any of the request data, make the following replacements:

  • PROJECT : the name of the project where you want the primary instance and read pool to reside.
  • REGION : the region for the read pool, such as us-east1 . The region must be the same as the primary instance.
  • TIER : the machine type you want to use for each read pool node in the read pool, such as db-perf-optimized-N-4 .
  • PRIMARY_INSTANCE_NAME : the name of the primary instance.
  • READ_POOL_NAME : the name you want to use for the read pool, such as my-read-pool .
  • DATABASE_VERSION : the database version you want to use. For example, MYSQL_8_0_37 .
  • NODE_COUNT : the number of read pool nodes you want in the read pool. Choose any number from 1 to 20 .
  • FULL_NETWORK_NAME : the full network path where you want the read pool to reside, such as projects/vpc-host-project/global/networks/my-network-name .

HTTP method and URL:

POST https://sqladmin.googleapis.com/sql/v1beta4/projects/ PROJECT 
/instances

Request JSON body:

{
  "name": " READ_POOL_NAME 
",
  "masterInstanceName": " PRIMARY_INSTANCE_NAME 
",
  "project": " PROJECT 
",
  "databaseVersion": " DATABASE_VERSION 
",
  "region": " REGION 
",
  "instanceType": "READ_POOL_INSTANCE",
  "nodeCount": NODE_COUNT 
,
  "settings": {
    "tier": " TIER 
",
    "edition": "ENTERPRISE_PLUS",
    "ipConfiguration": {
      "ipv4Enabled": false,
      "privateNetwork": " FULL_NETWORK_NAME 
"
    }
  }
}

To send your request, expand one of these options:

You should receive a JSON response similar to the following:

Convert a read replica to a read pool

You can convert an existing Cloud SQL Enterprise Plus edition read replica into a read pool by specifying the number of nodes in the pool. During this conversion process, the replica IP will become the read pool IP (the read endpoint), so existing clients can connect to the pool without reconfiguration.

The newly created read pool nodes will have the same machine type and configuration as the original read replica. Changing this machine type or configuration requires a separate operation. This operation is only supported for zonal read replicas. To convert a highly available (HA) read replica to a read pool, you must first convert it to a zonal read replica.

For more information, see Edit read pool configuration .

gcloud

For information about installing and getting started with the gcloud CLI, see Install the gcloud CLI . For information about starting Cloud Shell, see Use Cloud Shell .

Use the following gcloud sql instances patch command to convert a read replica for use with a read pool:

  
gcloud  
sql  
instances  
patch  
 READ_REPLICA_NAME 
  
 \ 
  
--instance-type = 
READ_POOL_INSTANCE  
--node-count = 
 NODE_COUNT 
  

Make the following replacements:

  • READ_REPLICA_NAME : the name of the read replica you want to convert.
  • NODE_COUNT : the number of read pool nodes you want in the read pool. Choose any number from 1 to 20 .

Terraform

To convert a read replica to a read pool, use a Terraform resource . The manifest looks similar to the one you used in Create a read replica . Then, complete the following steps:

  • Change the instance_type attribute from "READ_REPLICA_INSTANCE" to "READ_POOL_INSTANCE" and the node_count attribute to the number of nodes you want to use.
  • If you previously set it, clear the settings.availability_type attribute.

REST v1

Use the patch method of the instances resource to convert a read replica to a read pool.

Before using any of the request data, make the following replacements:

  • READ_REPLICA_NAME : the name of the read replica you wish to convert, such as my-read-replica .
  • NODE_COUNT : the number of read pool nodes you want in the read pool. Choose any number from 1 to 20 .

HTTP method and URL:

PATCH https://sqladmin.googleapis.com/v1/projects/ PROJECT 
/instances/ READ_REPLICA_NAME 

Request JSON body:

{
  "instanceType": "READ_POOL_INSTANCE",
  "nodeCount": NODE_COUNT 
}

To send your request, expand one of these options:

You should receive a JSON response similar to the following:

REST v1beta4

Use the patch method of the instances resource to convert a read replica to a read pool.

Before using any of the request data, make the following replacements:

  • READ_REPLICA_NAME : the name of the read replica you wish to convert, such as my-read-replica .
  • NODE_COUNT : the number of read pool nodes you want in the read pool. Choose any number from 1 to 20 .

HTTP method and URL:

PATCH https://sqladmin.googleapis.com/sql/v1beta4/projects/ PROJECT 
/instances/ READ_REPLICA_NAME 

Request JSON body:

{
  "instanceType": "READ_POOL_INSTANCE",
  "nodeCount": NODE_COUNT 
}

To send your request, expand one of these options:

You should receive a JSON response similar to the following:

Convert a read pool to a read replica

gcloud

For information about installing and getting started with the gcloud CLI, see Install the gcloud CLI . For information about starting Cloud Shell, see Use Cloud Shell .

Use the following gcloud sql instances patch command to convert a read replica for use with a read pool:

  
gcloud  
sql  
instances  
patch  
 READ_POOL_NAME 
  
 \ 
  
--instance-type = 
READ_REPLICA_INSTANCE  
--availability-type = 
ZONAL  

Make the following replacements:

  • READ_POOL_NAME : the name of the read pool you want to convert.

Terraform

To convert a read pool to a read replica, use a Terraform resource . The manifest looks similar to the one you used in Create a read pool . Then, change the instance_type attribute from "READ_POOL_INSTANCE" to "READ_REPLICA_INSTANCE" , clear the node_count attribute, and set the settings.availability_type attribute to ZONAL .

REST v1

Use the patch method of the instances resource to convert a read pool to a read replica.

Before using any of the request data, make the following replacements:

  • READ_POOL_NAME : the name of the read pool, such as my-read-pool .

HTTP method and URL:

PATCH https://sqladmin.googleapis.com/v1/projects/ PROJECT 
/instances/ READ_POOL_NAME 

Request JSON body:

{
  "instanceType": "READ_REPLICA_INSTANCE",
  "settings": {
    "availabilityType": "ZONAL"
  }
}

To send your request, expand one of these options:

You should receive a JSON response similar to the following:

REST v1beta4

Use the patch method of the instances resource to convert a read pool to a read replica.

Before using any of the request data, make the following replacements:

  • READ_POOL_NAME : the name of the read pool, such as my-read-pool .

HTTP method and URL:

PATCH https://sqladmin.googleapis.com/sql/v1beta4/projects/ PROJECT 
/instances/ READ_POOL_NAME 

Request JSON body:

{
  "instanceType": "READ_REPLICA_INSTANCE",
  "settings": {
    "availabilityType": "ZONAL"
  }
}

To send your request, expand one of these options:

You should receive a JSON response similar to the following:

View read pool information

gcloud

For information about installing and getting started with the gcloud CLI, see Install the gcloud CLI . For information about starting Cloud Shell, see Use Cloud Shell .

Use the following gcloud sql instances describe command to describe the read pool:

  
gcloud  
sql  
instances  
describe  
 READ_POOL_NAME 
  

Make the following replacements:

  • READ_POOL_NAME : the name of the read pool you want to describe.

An example response with IP address and node information, might look similar to the following:

  
 ... 
  
 connectionName 
 : 
  
 my-project:us-central1:read-pool 
  
 ipAddresses 
 : 
  
 - 
  
 ipAddress 
 : 
  
 10.3.0.108 
  
 type 
 : 
  
 PRIVATE 
  
 nodeCount 
 : 
  
 2 
  
 nodes 
 : 
  
 - 
  
 dnsName 
 : 
  
 c5bdacb09ffc.j10o8yqc7pve.us-central1.sql.goog. 
  
 gceZone 
 : 
  
 us-central1-f 
  
 ipAddresses 
 : 
  
 - 
  
 ipAddress 
 : 
  
 10.3.0.112 
  
 type 
 : 
  
 PRIVATE 
  
 name 
 : 
  
 read-pool-node-01 
  
 state 
 : 
  
 RUNNABLE 
  
 - 
  
 dnsName 
 : 
  
 8f77c454d6b2.j10o8yqc7pve.us-central1.sql.goog. 
  
 gceZone 
 : 
  
 us-central1-c 
  
 ipAddresses 
 : 
  
 - 
  
 ipAddress 
 : 
  
 10.3.0.113 
  
 type 
 : 
  
 PRIVATE 
  
 name 
 : 
  
 read-pool-node-02 
  
 state 
 : 
  
 RUNNABLE 
  

REST v1

Use the get method to view read pool details.

Before using any of the request data, make the following replacements:

  • PROJECT : the name of the project where the read pool resides.
  • READ_POOL_NAME : the name of the read pool, such as my-read-pool .

HTTP method and URL:

GET https://sqladmin.googleapis.com/v1/projects/ PROJECT 
/instances/ READ_POOL_NAME 

To send your request, expand one of these options:

You should receive a JSON response similar to the following:

REST v1beta4

Use the get method to view read pool details.

Before using any of the request data, make the following replacements:

  • PROJECT : the name of the project where the read pool resides.
  • READ_POOL_NAME : the name of the read pool, such as my-read-pool .

HTTP method and URL:

GET https://sqladmin.googleapis.com/sql/v1beta4/projects/ PROJECT 
/instances/ READ_POOL_NAME 

To send your request, expand one of these options:

You should receive a JSON response similar to the following:

{
  [...],
  "connectionName": "my-project:us-central1:read-pool",
  "ipAddresses": [
    {
      "type": "PRIVATE",
      "ipAddress": "10.3.0.108"
    }
  ],
  "nodeCount": 2,
  "nodes": [
    {
      "ipAddresses": [
        {
          "type": "PRIVATE",
          "ipAddress": "10.3.0.112"
        }
      ],                                                                                                                 
      "name": "read-pool-node-01",
      "gceZone": "us-central1-f",
      "dnsName": "c5bdacb09ffc.j10o8yqc7pve.us-central1.sql.goog.",
      "state": "RUNNABLE"
    },
    {
      "ipAddresses": [
        {
          "type": "PRIVATE",
          "ipAddress": "10.3.0.113"
        }
      ],
      "name": "read-pool-node-02",
      "gceZone": "us-central1-c",
      "dnsName": "8f77c454d6b2.j10o8yqc7pve.us-central1.sql.goog.",
      "state": "RUNNABLE"
    }
  ]
}

Add or remove read pool nodes

The following steps scale a read pool in or out by modifying the number of read pool nodes in the read pool. Some operation limitations apply. For more information, see Read pool limitations .

gcloud

For information about installing and getting started with the gcloud CLI, see Install the gcloud CLI . For information about starting Cloud Shell, see Use Cloud Shell .

Use the following gcloud sql instances patch command to scale the read pool:

  
gcloud  
sql  
instances  
patch  
 READ_POOL_NAME 
  
 \ 
  
--node-count = 
 NODE_COUNT 
  

Make the following replacements:

  • READ_POOL_NAME : the name of the read pool.
  • NODE_COUNT : the number of read pool nodes you want in the read pool. Choose any number from 1 to 20 .

Terraform

To change the number of read pool nodes, update an existing Terraform resource . The manifest looks similar to the one you used in Create a read pool . Then, change the node_count attribute to the number of nodes you want to use.

REST v1

Use the patch method to scale a read pool in or out by modifying the number of read pool nodes in the read pool.

Before using any of the request data, make the following replacements:

  • PROJECT : the name of the project where the read pool resides.
  • NODE_COUNT : the number of read pool nodes you want in the read pool. Choose any number from 1 to 20 .

HTTP method and URL:

PATCH https://sqladmin.googleapis.com/v1/projects/ PROJECT 
/instances/ READ_POOL_NAME 

Request JSON body:

{
  "nodeCount": NODE_COUNT 
}

To send your request, expand one of these options:

You should receive a JSON response similar to the following:

REST v1beta4

Use the patch method to scale a read pool in or out by modifying the number of read pool nodes in the read pool.

Before using any of the request data, make the following replacements:

  • PROJECT : the name of the project where the read pool resides.
  • NODE_COUNT : the number of read pool nodes you want in the read pool. Choose any number from 1 to 20 .

HTTP method and URL:

PATCH https://sqladmin.googleapis.com/sql/v1beta4/projects/ PROJECT 
/instances/ READ_POOL_NAME 

Request JSON body:

{
  "nodeCount": NODE_COUNT 
}

To send your request, expand one of these options:

You should receive a JSON response similar to the following:

Edit read pool configuration

The following steps show you how to edit read pool configuration. For more detailed information, see About instance settings and Edit instances .

gcloud

For information about installing and getting started with the gcloud CLI, see Install the gcloud CLI . For information about starting Cloud Shell, see Use Cloud Shell .

Use the following gcloud sql instances patch command to vertically scale the read pool, for example, by modifying the machine type:

  
gcloud  
sql  
instances  
patch  
 READ_POOL_NAME 
  
 \ 
  
--tier = 
 TIER 
  

Make the following replacements:

  • READ_POOL_NAME : the name of the read pool.
  • TIER : the machine type you want to apply to each read pool node in the read pool, such as db-perf-optimized-N-8 .

Terraform

To edit the read pool configuration, update an existing Terraform resource . The manifest looks similar to the one you used in Create a read pool . Then, update the attributes you want to change in the settings field. For example, change the settings.tier attribute to a different machine type.

REST v1

Use the patch method to modify read pool node configuration. Settings are uniformly applied across all read pool nodes in the read pool.

Before using any of the request data, make the following replacements:

  • PROJECT : the name of the project where the read pool resides.
  • TIER : the machine type you want to use for each read pool node in the read pool, such as db-perf-optimized-N-4 .
  • READ_POOL_NAME : the name of the read pool, such as my-read-pool .

HTTP method and URL:

PATCH https://sqladmin.googleapis.com/v1/projects/ PROJECT 
/instances/ READ_POOL_NAME 

Request JSON body:

{
  "settings": {
    "tier": " TIER 
"
  }
}

To send your request, expand one of these options:

You should receive a JSON response similar to the following:

REST v1beta4

Use the patch method to modify read pool node configuration. Settings are uniformly applied across all read pool nodes in the read pool.

Before using any of the request data, make the following replacements:

  • PROJECT : the name of the project where the read pool resides.
  • TIER : the machine type you want to use for each read pool node in the read pool, such as db-perf-optimized-N-4 .
  • READ_POOL_NAME : the name of the read pool, such as my-read-pool .

HTTP method and URL:

PATCH https://sqladmin.googleapis.com/sql/v1beta4/projects/ PROJECT 
/instances/ READ_POOL_NAME 

Request JSON body:

{
  "settings": {
    "tier": " TIER 
"
  }
}

To send your request, expand one of these options:

You should receive a JSON response similar to the following:

Connect to a read pool

There are many ways to connect to a read pool. The following steps show one way, namely, connecting to a read pool with a private IP address by creating a VM in the same VPC network to serve as the connection source.

For more information about other ways you can configure connectivity to a Cloud SQL instance, see About Cloud SQL connections . The connection methods usually require you to first obtain the IP address or connection name of the instance, as described in View read pool information . Read pools support most of the connection methods available for other Cloud SQL instances, with some limitations .

If connecting using the Cloud SQL Auth Proxy or the Cloud SQL Connectors, make sure to update to the latest version. For read pool support, the minimum required versions include the following:

  • Cloud SQL Auth Proxy: v2.15.2
  • Cloud SQL Python Connector: v1.18.0
  • Cloud SQL Go Connector: v1.16.0
  • Cloud SQL Node Connector: v1.7.0
  • Cloud SQL Java Connector: v1.24.0

Console

To connect to a read pool, complete the following steps:

  1. In the Google Cloud console, go to the Cloud SQL Instances page.

    Go to Cloud SQL Instances

    You're taken to the instance Overview page. Click into the new read pool to view the details including its private IP address. In the Connect to this instance section, copy and save the instance's Connection name . The connection name is in the format projectID:region:instanceID . You'll use this connection name later when starting the Cloud SQL Auth Proxy.
  2. Create a Compute Engine VM .
  3. Open two SSH connections to the Compute Engine VM . These are used in subsequent steps to run the Cloud SQL Auth Proxy and run the database client.
  4. Install the client .
  5. Install the Cloud SQL Auth Proxy .
  6. Start the Cloud SQL Auth Proxy .
  7. Connect to your Cloud SQL instance .

For more information, see Connect to a Cloud SQL instance with private IP .

Delete a read pool

gcloud

For information about installing and getting started with the gcloud CLI, see Install the gcloud CLI . For information about starting Cloud Shell, see Use Cloud Shell .

Use the following gcloud sql instances delete command to delete a read pool:

  
gcloud  
sql  
instances  
delete  
 READ_POOL_NAME 
  

Make the following replacements:

  • READ_POOL_NAME : the name of the read pool you want to delete.

REST v1

Use the delete method to delete a read pool.

Before using any of the request data, make the following replacements:

  • PROJECT : the name of the project where the read pool resides.
  • READ_POOL_NAME : the name of the read pool, such as my-read-pool .

HTTP method and URL:

DELETE https://sqladmin.googleapis.com/v1/projects/ PROJECT 
/instances/ READ_POOL_NAME 

To send your request, expand one of these options:

You should receive a JSON response similar to the following:

REST v1beta4

Use the delete method to delete a read pool.

Before using any of the request data, make the following replacements:

  • PROJECT : the name of the project where the read pool resides.
  • READ_POOL_NAME : the name of the read pool, such as my-read-pool .

HTTP method and URL:

DELETE https://sqladmin.googleapis.com/sql/v1beta4/projects/ PROJECT 
/instances/ READ_POOL_NAME 

To send your request, expand one of these options:

You should receive a JSON response similar to the following:

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