Best practices for importing and exporting
The following are best practices to consider when importing and exporting data:
- Don't use Cloud Storage Requester Pays buckets
- Compress data to reduce cost
- Reduce long-running import and export processes
Don't use Cloud Storage Requester Pays buckets
You cannot use a Cloud Storage bucket that has Requester Pays enabled for imports and exports from Cloud SQL.
Compress data to reduce cost
Cloud SQL supports importing and exporting both compressed and uncompressed files. Compression can save significant storage space on Cloud Storage and reduce your storage costs, especially when you are exporting large instances.
When you export a BAK file, use a .gz
file extension to compress the data. When you import a file with an
extension of .gz, it is decompressed automatically.
Reduce long-running import and export processes
Imports and exports into Cloud SQL using the import functionality (with a Cloud Storage bucket) can take a long time to complete, depending on the size of the database. This can have the following impacts:
- You cannot stop a long-running operation.
- You can perform only one import or export operation at a time for each instance.
You can decrease the amount of time it takes to complete each operation by using the Cloud SQL import or export functionality with smaller batches of data.
For exports, you can use serverless export to minimize the impact on database performance and allow other operations to run on your instance while an export is running.
For more tips, see Diagnosing Issues with Cloud SQL Instances.
Tips for long-running import and export processes
Imports and exports into Cloud SQL using the import functionality (with a Cloud Storage bucket) can take a long time to complete, depending on the size of the database. This can have the following impacts:
- You cannot stop a long-running operation.
- You can perform only one import or export operation at a time for each instance.
You can decrease the amount of time it takes to complete each operation by using the Cloud SQL import or export functionality with smaller batches of data.
For exports, you can use serverless export to minimize the impact on database performance and allow other operations to run on your instance while an export is running.
Troubleshooting
Click the links in the table for details:
| For this problem... | The issue might be... | Try this... |
|---|---|---|
| Can't see the operation status. | The user interface only shows success or failure. | Use these database commands to find out more. |
| Export is taking too long. | Cloud SQL does not support concurrent synchronous operations. | Use export offloading. Learn more. |
| Import is taking too long. | Too many active connections can interfere with import operations. | Close unused connections, or restart the Cloud SQL instance before beginning an import operation. |
| Import fails. | Exported file may contain database users who do not yet exist. | Create the database users before doing the import. |
| Connection closed during the export operation. | Query must produce data within first seven minutes. | Test the query manually. Learn more. |
| Unknown error during export. | Possible bandwidth issue. | Ensure that both the instance and the Cloud Storage bucket are in the same region. |
| You want to automate exports. | Cloud SQL does not provide a way to automate exports. | Build your own pipeline to perform this functionality. Learn more. |
ERROR_RDBMS: system error occurred. |
Cloud Storage permissions or non-existent table. | Check permissions OR ensure table exists. |
Can't see the operation status
You can't see the status of an ongoing operation.
The issue might be
The Google Cloud Console reports only success or failure when done, and is not designed to return warnings.
Things to try
Connect to the database and run SHOW WARNINGS.
Export is taking too long
Export is taking too long, blocking other operations.
The issue might be
Cloud SQL does not support concurrent synchronous operations.
Things to try
Try exporting smaller datasets at a time.
Import is taking too long
Import is taking too long, blocking other operations.
The issue might be
Too many active connections can interfere with import operations. Connections consume CPU and memory, limiting the resources available.
Things to try
Close unused operations. Check CPU and memory usage to make sure there are plenty of resources available. The best way to ensure maximum resources for the import operation is to restart the instance before beginning the operation. A restart:
- Closes all connections.
- Ends any tasks that may be consuming resources.
Import fails
Import fails when one or more users referenced in the exported SQL dump file does not exist.
The issue might be
Before importing a SQL dump, all the database users who own objects or were granted permissions on objects in the dumped database must exist. If they do not, the restore fails to recreate the objects with the original ownership and/or permissions.
Things to try
Create the database users before importing the SQL dump.
Connection closed during the export operation
Connection closed during the export operation.
The issue might be
The connection to Cloud Storage may be timing out because the query running in the export is not producing any data within the first seven minutes since the export is initiated.
Things to try
Test the query manually by connecting from any client and sending the output of your query to STDOUT with the command below:
COPY (INSERT_YOUR_QUERY_HERE) TO STDOUT WITH ( FORMAT csv, DELIMITER ',', ENCODING 'UTF8', QUOTE '"', ESCAPE '"' ).
This is expected behavior since when the export is initiated, the client is expected to start sending data right away. Keeping the connection with no data sent ends up breaking the connection and eventually resulting in the export failing and leaving the operation in an uncertain state. Also, this is what the error message from gcloud is trying to say with this message:
operation is taking longer than expected.
Unknown error during export
You see the error message Unknown error while trying to export a
database to a Cloud Storage bucket.
The issue might be
The transfer might be failing due to a bandwidth issue.
Things to try
The Cloud SQL instance may be located in a different region from the Cloud Storage bucket. Reading and writing data from one continent to another involves a lot of network usage, and can cause intermittent issues like this. Check the regions of your instance and bucket.
Want to automate exports
You want to automate exports.
The issue might be
Cloud SQL does not provide a way to automate exports.
Things to try
You could build your own automated export system using Google Cloud products such as Cloud Scheduler, Pub/Sub, and Cloud Functions.
ERROR_RDBMS system error occurred
You see the error message [ERROR_RDBMS] system error occurred.
The issue might be
- The user might not have all the Cloud Storage permissions it needs.
- The database table might not exist.
Things to try
- Check that you have at least
WRITERpermissions on the bucket andREADERpermissions on the export file. For more information on configuring access control in Cloud Storage, see Create and Manage Access Control Lists. - Ensure the table exists. If the table exists, confirm that you have the correct permissions on the bucket.