This page describes how to manage read replicas. These operations include disabling and enabling replication, promoting a replica, configuring parallel replication, and checking the replication status.
For more information about how replication works, see Replication in Cloud SQL.
This page applies to replicas of a Cloud SQL instance. To set up a Cloud SQL instance to act as a publisher to an external subscriber, see Configure external replicas.
Important: Before using this feature, review the limitations. Additionally, note that this feature only applies to the following versions of Cloud SQL for SQL Server: SQL Server 2017 Enterprise, SQL Server 2019 Enterprise, and SQL Server 2022 Enterprise. Disable replicationBy default, a replica starts with replication enabled. However, you can disable replication, for example, to debug or analyze the state of an instance. When you are ready, you explicitly re-enable replication. Disabling or re-enabling replication doesn't restart the replica instance.
Disabling replication does not stop the replica instance; it becomes a read-only instance that is no longer replicating from its primary instance. You continue to be charged for the instance. On the disabled replica, you can re-enable replication, delete the replica, or promote the replica to a stand-alone instance.
When you disable the replication for an extended period of time, your disk storage requirements might increase. For example, your instance might accumulate transactional logs to let you resume replication when you re-enable replication. To avoid increasing disk storage requirements, instead of disabling replication for an extended period of time, consider promoting the replica or creating a clone of the primary instance.
To disable replication:
ConsoleIn the Google Cloud console, go to the Cloud SQL Instances page.
gcloud sql instances patch REPLICA_NAME \ --no-enable-database-replicationREST v1
To execute this cURL command at a command line prompt, you acquire an access token by using the gcloud auth print-access-token command. You can also use the APIs Explorer on the Instances:patch page to send the REST API request.
Before using any of the request data, make the following replacements:
HTTP method and URL:
PATCH https://sqladmin.googleapis.com/v1/projects/project-id/instances/replica-name
Request JSON body:
{ "settings": { "databaseReplicationEnabled": "False" } }
To send your request, expand one of these options:
curl (Linux, macOS, or Cloud Shell) Note: The following command assumes that you have logged in to thegcloud
CLI with your user account by running gcloud init
or gcloud auth login
, or by using Cloud Shell, which automatically logs you into the gcloud
CLI . You can check the currently active account by running gcloud auth list
.
Save the request body in a file named request.json
, and execute the following command:
curl -X PATCH \PowerShell (Windows) Note: The following command assumes that you have logged in to the
-H "Authorization: Bearer $(gcloud auth print-access-token)" \
-H "Content-Type: application/json; charset=utf-8" \
-d @request.json \
"https://sqladmin.googleapis.com/v1/projects/project-id/instances/replica-name"
gcloud
CLI with your user account by running gcloud init
or gcloud auth login
. You can check the currently active account by running gcloud auth list
.
Save the request body in a file named request.json
, and execute the following command:
$cred = gcloud auth print-access-token
$headers = @{ "Authorization" = "Bearer $cred" }Invoke-WebRequest `
-Method PATCH `
-Headers $headers `
-ContentType: "application/json; charset=utf-8" `
-InFile request.json `
-Uri "https://sqladmin.googleapis.com/v1/projects/project-id/instances/replica-name" | Select-Object -Expand Content
You should receive a JSON response similar to the following:
Response{ "kind": "sql#operation", "targetLink": "https://sqladmin.googleapis.com/v1/projects/project-id/instances/replica-name", "status": "PENDING", "user": "user@example.com", "insertTime": "2020-01-21T22:43:37.981Z", "operationType": "UPDATE", "name": "operation-id", "targetId": "replica-name", "selfLink": "https://sqladmin.googleapis.com/v1/projects/project-id/operations/operation-id", "targetProject": "project-id" }REST v1beta4
To execute this cURL command at a command line prompt, you acquire an access token by using the gcloud auth print-access-token command. You can also use the APIs Explorer on the Instances:patch page to send the REST API request.
Before using any of the request data, make the following replacements:
HTTP method and URL:
PATCH https://sqladmin.googleapis.com/sql/v1beta4/projects/project-id/instances/replica-name
Request JSON body:
{ "settings": { "databaseReplicationEnabled": "False" } }
To send your request, expand one of these options:
curl (Linux, macOS, or Cloud Shell) Note: The following command assumes that you have logged in to thegcloud
CLI with your user account by running gcloud init
or gcloud auth login
, or by using Cloud Shell, which automatically logs you into the gcloud
CLI . You can check the currently active account by running gcloud auth list
.
Save the request body in a file named request.json
, and execute the following command:
curl -X PATCH \PowerShell (Windows) Note: The following command assumes that you have logged in to the
-H "Authorization: Bearer $(gcloud auth print-access-token)" \
-H "Content-Type: application/json; charset=utf-8" \
-d @request.json \
"https://sqladmin.googleapis.com/sql/v1beta4/projects/project-id/instances/replica-name"
gcloud
CLI with your user account by running gcloud init
or gcloud auth login
. You can check the currently active account by running gcloud auth list
.
Save the request body in a file named request.json
, and execute the following command:
$cred = gcloud auth print-access-token
$headers = @{ "Authorization" = "Bearer $cred" }Invoke-WebRequest `
-Method PATCH `
-Headers $headers `
-ContentType: "application/json; charset=utf-8" `
-InFile request.json `
-Uri "https://sqladmin.googleapis.com/sql/v1beta4/projects/project-id/instances/replica-name" | Select-Object -Expand Content
You should receive a JSON response similar to the following:
Response{ "kind": "sql#operation", "targetLink": "https://sqladmin.googleapis.com/sql/v1beta4/projects/project-id/instances/replica-name", "status": "PENDING", "user": "user@example.com", "insertTime": "2020-01-21T22:43:37.981Z", "operationType": "UPDATE", "name": "operation-id", "targetId": "replica-name", "selfLink": "https://sqladmin.googleapis.com/sql/v1beta4/projects/project-id/operations/operation-id", "targetProject": "project-id" }Enable replication
If a replica has not been replicating for a long time, it will take longer for it to catch up to the primary instance. In this case, delete the replica and create a new one.
To enable replication:
ConsoleIn the Google Cloud console, go to the Cloud SQL Instances page.
gcloud sql instances patch REPLICA_NAME \ --enable-database-replicationREST v1
To execute this cURL command at a command line prompt, you acquire an access token by using the gcloud auth print-access-token command. You can also use the APIs Explorer on the Instances:patch page to send the REST API request.
Before using any of the request data, make the following replacements:
HTTP method and URL:
PATCH https://sqladmin.googleapis.com/v1/projects/project-id/instances/replica-name
Request JSON body:
{ "settings": { "databaseReplicationEnabled": "True" } }
To send your request, expand one of these options:
curl (Linux, macOS, or Cloud Shell) Note: The following command assumes that you have logged in to thegcloud
CLI with your user account by running gcloud init
or gcloud auth login
, or by using Cloud Shell, which automatically logs you into the gcloud
CLI . You can check the currently active account by running gcloud auth list
.
Save the request body in a file named request.json
, and execute the following command:
curl -X PATCH \PowerShell (Windows) Note: The following command assumes that you have logged in to the
-H "Authorization: Bearer $(gcloud auth print-access-token)" \
-H "Content-Type: application/json; charset=utf-8" \
-d @request.json \
"https://sqladmin.googleapis.com/v1/projects/project-id/instances/replica-name"
gcloud
CLI with your user account by running gcloud init
or gcloud auth login
. You can check the currently active account by running gcloud auth list
.
Save the request body in a file named request.json
, and execute the following command:
$cred = gcloud auth print-access-token
$headers = @{ "Authorization" = "Bearer $cred" }Invoke-WebRequest `
-Method PATCH `
-Headers $headers `
-ContentType: "application/json; charset=utf-8" `
-InFile request.json `
-Uri "https://sqladmin.googleapis.com/v1/projects/project-id/instances/replica-name" | Select-Object -Expand Content
You should receive a JSON response similar to the following:
Response{ "kind": "sql#operation", "targetLink": "https://sqladmin.googleapis.com/v1/projects/project-id/instances/replica-name", "status": "PENDING", "user": "user@example.com", "insertTime": "2020-01-21T22:43:37.981Z", "operationType": "UPDATE", "name": "operation-id", "targetId": "replica-name", "selfLink": "https://sqladmin.googleapis.com/v1/projects/project-id/operations/operation-id", "targetProject": "project-id" }REST v1beta4
To execute this cURL command at a command line prompt, you acquire an access token by using the gcloud auth print-access-token command. You can also use the APIs Explorer on the Instances:patch page to send the REST API request.
Before using any of the request data, make the following replacements:
HTTP method and URL:
PATCH https://sqladmin.googleapis.com/sql/v1beta4/projects/project-id/instances/replica-name
Request JSON body:
{ "settings": { "databaseReplicationEnabled": "True" } }
To send your request, expand one of these options:
curl (Linux, macOS, or Cloud Shell) Note: The following command assumes that you have logged in to thegcloud
CLI with your user account by running gcloud init
or gcloud auth login
, or by using Cloud Shell, which automatically logs you into the gcloud
CLI . You can check the currently active account by running gcloud auth list
.
Save the request body in a file named request.json
, and execute the following command:
curl -X PATCH \PowerShell (Windows) Note: The following command assumes that you have logged in to the
-H "Authorization: Bearer $(gcloud auth print-access-token)" \
-H "Content-Type: application/json; charset=utf-8" \
-d @request.json \
"https://sqladmin.googleapis.com/sql/v1beta4/projects/project-id/instances/replica-name"
gcloud
CLI with your user account by running gcloud init
or gcloud auth login
. You can check the currently active account by running gcloud auth list
.
Save the request body in a file named request.json
, and execute the following command:
$cred = gcloud auth print-access-token
$headers = @{ "Authorization" = "Bearer $cred" }Invoke-WebRequest `
-Method PATCH `
-Headers $headers `
-ContentType: "application/json; charset=utf-8" `
-InFile request.json `
-Uri "https://sqladmin.googleapis.com/sql/v1beta4/projects/project-id/instances/replica-name" | Select-Object -Expand Content
You should receive a JSON response similar to the following:
Response{ "kind": "sql#operation", "targetLink": "https://sqladmin.googleapis.com/sql/v1beta4/projects/project-id/instances/replica-name", "status": "PENDING", "user": "user@example.com", "insertTime": "2020-01-21T22:43:37.981Z", "operationType": "UPDATE", "name": "operation-id", "targetId": "replica-name", "selfLink": "https://sqladmin.googleapis.com/sql/v1beta4/projects/project-id/operations/operation-id", "targetProject": "project-id" }
Promoting a read replica stops replication and converts the instance to a standalone Cloud SQL primary instance with read and write capabilities.
When promoted, read replicas are automatically configured with backups, but they aren't automatically configured as high availability (HA) instances. You can enable high availability after promoting the replica just as you would for any non-replica instance. Configuring a read replica for high availability is done the same way as for a primary instance. Learn more about configuring the instance for high availability.
See Promoting replicas for regional migration or disaster recovery to learn more about use cases for cross-region replicas.Before promoting a read replica, if the primary is still available and serving clients, you should do the following:
seconds_behind_master
metric.Otherwise, a newly promoted instance may be missing some transactions that were committed to the primary instance.
To promote a replica to a standalone instance:
Confirm that the promoted instance is configured correctly. In particular, consider configuring the instance for high availability if needed.
Check replication statusCurrently, you should use T-SQL queries or SSMS to monitor replication status. For more information, see the following:
Troubleshoot Issue Troubleshooting Read replica didn't start replicating on creation. There's probably a more specific error in the log files. Inspect the logs in Cloud Logging to find the actual error. Unable to create read replica - invalidFlagValue error. One of the flags in the request is invalid. It could be a flag you provided explicitly or one that was set to a default value.First, check that the value of the max_connections
flag is greater than or equal to the value on the primary.
If the max_connections
flag is set appropriately, inspect the logs in Cloud Logging to find the actual error.
If the error is: set Service Networking service account as servicenetworking.serviceAgent role on consumer project
, then disable and re-enable the Service Networking API
. This action creates the service account necessary to continue with the process.
Restart the replica instance to reclaim the temporary memory space.
Replication stopped. The maximum storage limit was reached and automatic storage increase isn't enabled. Edit the instance to enable automatic storage increase
.
DELETE ... WHERE field < 50000000
cause replication lag with row-based replication since a huge number of updates are piled up on the replica.Some possible solutions include:
Recreate the replica after stopping all running queries.
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