Diagnosing issues with Cloud SQL instances

This page contains a list of the most frequent issues you might run into when working with Cloud SQL instances and steps you can take to address them. Also review the Known issues, Troubleshooting, and Support page pages.

Viewing logs

To see information about recent operations, you can view the Cloud SQL instance operation logs or the MySQL error logs.

Instance unresponsive

If your instance stops responding to connections or performance is degraded, make sure it conforms to the Operational Guidelines. If it does not conform to these guidelines, it is not covered by the Cloud SQL SLA.

Connection issues

See the Debugging connection issues page or the Connectivity section in the troubleshooting page for help with connection problems.

Instance issues

Backups

For the best performance for backups, keep the number of tables to a reasonable number.

For other backups issues, see the Backups section in the troubleshooting page.

Import and export

Imports and exports in Cloud SQL are the same as using the mysqldump utility, except that with the Cloud SQL import/export feature, you transfer data using a Cloud Storage bucket.

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 Cloud SQL instance 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.

Other points to keep in mind when importing:

  • If your import is crashing, it could be due to an out-of-memory (OOM) error. If this is the case, you can try using MySQL commands directly to add the --extended-insert=FALSE --complete-insert parameters. These parameters reduce the speed of your import, but also reduce the amount of memory the import requires.

For other import and export issues, see the Import and export section in the troubleshooting page.

Disk space

If your instance reaches the maximum storage amount allowed, writes to the database fail. If you delete data, for example, by dropping a table, the space freed is not reflected in the reported Storage Used of the instance. See the FAQ How can I reclaim the space from a dropped table? for an explanation of this behavior.

Reaching the maximum storage limit can also cause the instance to get stuck in restart.

Avoid data corruption

Avoid generated columns

Due to an issue in MySQL, using generated columns might result in data corruption. For more information, see MySQL bug #82736.

Clean shutdowns

When Cloud SQL shuts down an instance (e.g, for maintenance), no new connections are sent to the instance and existing connections are ended. The amount of time mysqld has to shutdown is capped to 1 minute. If the shutdown does not complete in that time, the mysqld process is forcefully stopped. This can result in disk writes being aborted mid-way through.

Database engines

InnoDB is the only supported storage engine for MySQL instances because it is more resistant to table corruption than other MySQL storage engines, such as MyISAM.

By default, Cloud SQL database tables are created using the InnoDB storage engine. If your CREATE TABLE syntax includes an ENGINE option specifying a storage engine other than InnoDB, for example ENGINE = MyISAM, the table is not created and you see error messages like the following example:

ERROR 3161 (HY000): Storage engine MyISAM is disabled (Table creation is disallowed).

You can avoid this error by removing the ENGINE = MyISAM option from the CREATE TABLE command. Doing so creates the table with the InnoDB storage engine.

Changes to system tables

MySQL system tables use the MyISAM storage engine, including all tables in the mysql database, for example mysql.user and mysql.db. These tables are vulnerable to unclean shutdowns; issue the FLUSH CHANGES command after making changes to these tables. If MyISAM corruption does occur, CHECK TABLE and REPAIR TABLE can get you back to good state (but not save data).

Global Transaction Identifiers (GTID)

All MySQL instances have GTID enabled automatically. Having GTID enabled protects against data loss during replica creation and failover, and makes replication more robust. However, GTID comes with some limitations imposed by MySQL, as documented in the MySQL manual. The following transactionally unsafe operations cannot be used with a GTID-enabled MySQL server:

  • CREATE TABLE ... SELECT statements;
  • CREATE TEMPORARY TABLE statements inside transactions;
  • Transactions or statements that affect both transactional and non-transactional tables.

If you use a transactionally unsafe transaction, you see an error message like the following example:

 Exception: SQLSTATE[HY000]: General error: 1786
 CREATE TABLE ... SELECT is forbidden when @@GLOBAL.ENFORCE_GTID_CONSISTENCY = 1.

Working with triggers and stored functions

If your instance has binary logging enabled, and you need to work with triggers or stored functions, make sure your instance has the log_bin_trust_function_creators flag set to on.

Suspended state

There are various reasons why Cloud SQL may suspend an instance, including:

  • Billing issues

    For example, if the credit card for the project's billing account has expired, the instance may be suspended. You can check the billing information for a project by going to the Google Cloud Console billing page, selecting the project, and viewing the billing account information used for the project. After you resolve the billing issue, the instance returns to runnable status within a few hours.

  • KMS key issues

    For example, if the KMS key version used to encrypt the user data in the Cloud SQL instance is not present, or if it has been disabled or destroyed. See Using customer-managed encryption keys (CMEK).

  • Legal issues

    For example, a violation of the Google Cloud Acceptable Use Policy may cause the instance to be suspended. For more information, see "Suspensions and Removals" in the Google Cloud Terms of Service.

  • Operational issues

    For example, if an instance is stuck in a crash loop (it crashes while starting or just after starting), Cloud SQL may suspend it.

While an instance is suspended, you can continue to view information about it or you can delete it, if billing issues triggered the suspension.

Cloud SQL users with Platinum, Gold, or Silver support packages can contact our support team directly about suspended instances. All users can use the earlier guidance along with the google-cloud-sql forum.

Performance

Overview

Cloud SQL supports performance-intensive workloads with up to 60,000 IOPS and no extra cost for I/O. IOPS and throughput performance depends on disk size, instance vCPU count, and I/O block size, among other factors.

Your instance's performance also depends on your choice of storage type and workload.

Learn more about:

Enable query logs

To tune the performance of your queries, you can configure Cloud SQL to log slow queries by adding the database flags --log_output='FILE' and --slow_query_log=on to your instance. This makes the log output available using the Logs Viewer in the Google Cloud Console. Note that Google Cloud's operations suite logging charges apply.

Do not set log_output to TABLE. Doing so can cause connection issues as described in Tips for working with flags.

Enable lock monitoring

InnoDB monitors provide information about the InnoDB storage engine's internal state, which you can use in performance tuning.

Access the instance using MySQL Client and obtain on-demand monitor output:

SHOW ENGINE INNODB STATUS\G

For explanations of the sections in the monitor output, see InnoDB Standard Monitor and Lock Monitor Output.

You can enable InnoDB monitors so that output is generated periodically to a file or a table, with performance degradation. For more information, see Enabling InnoDB Monitors.

Use performance schema

The MySQL Performance Schema is a feature for monitoring MySQL Server execution at a low level. The most accessible way to consume the stats generated in performance_schema is through MySQL Workbench Performance Reports functionality.

Keep a reasonable number of database tables

Database tables consume system resources. A large number can affect instance performance and availability, and cause the instance to lose its SLA coverage. Learn more.

General performance tips

. For slow database inserts, updates, or deletes, consider the following actions:
  • Check the locations of the writer and database; sending data a long distance introduces latency.

For slow database selects, consider the following:

  • Caching is important for read performance. Compare the size of your dataset to the size of RAM of your instance. Ideally, the entire dataset fits within 70% of the instance's RAM, in which case queries are not constrained to IO performance. If not, consider increasing the size of your instance's RAM.
  • If your workload consists of CPU intensive queries (sorting, regular expressions, other complex functions), your instance might be throttled; increase the vCPUs.
  • Check the location of the reader and database - latency affects read performance even more than write performance.
  • Investigate non-Cloud SQL specific performance improvements, such as adding appropriate indexing, reducing data scanned, and avoiding extra round trips.
  • If you observe poor performance executing queries, use EXPLAIN. EXPLAIN is a statement you add to other statements, like SELECT, and it returns information about how MySQL executes the statement. It works with SELECT, DELETE, INSERT, REPLACE, and UPDATE. For example, EXPLAIN SELECT * FROM myTable;.

    Use EXPLAIN to identify where you can:

    • Add indexes to tables to improve query performance. For example, make sure every field that you use as a JOIN key has an index on both tables.

    • Improve ORDER BY operations. If EXPLAIN shows "Using temporary; Using filesort" in the Extra column of the output, then intermediate results are stored in a file that is then sorted, which usually results in poor performance. In this case, take one of the following steps:

      • If possible, use indexes rather than sorting. See ORDER BY Optimization for more information.

      • Increase the size of the sort_buffer_size variable for the query session.

      • Use less RAM per row by declaring columns only as large as required.

    Troubleshooting

    For other Cloud SQL issues, see the troubleshooting page.

    Error messages

    For specific API error messages, see the Error messages reference page.

    Troubleshooting customer-managed encryption keys (CMEK)

    Cloud SQL administrator operations, such as create, clone, or update, might fail due to Cloud KMS errors, and missing roles or permissions. Common reasons for failure include a missing Cloud KMS key version, a disabled or destroyed Cloud KMS key version, insufficient IAM permissions to access the Cloud KMS key version, or the Cloud KMS key version is in a different region than the Cloud SQL instance. Use the following troubleshooting table to diagnose and resolve common problems.

    Customer-managed encryption keys troubleshooting table

    For this error... The issue might be... Try this...
    Per-product, per-project service account not found The service account name is incorrect. Make sure you created a service account for the correct user project.

    GO TO THE SERVICE ACCOUNTS PAGE.

    Cannot grant access to the service account The user account does not have permission to grant access to this key version. Add the Organization Administrator role on your user or service account.

    GO TO THE IAM ACCOUNTS PAGE

    Cloud KMS key version is destroyed The key version is destroyed. If the key version is destroyed, you cannot use it to encrypt or decrypt data.
    Cloud KMS key version is disabled The key version is disabled. Re-enable the Cloud KMS key version.

    GO TO THE CRYPTO KEYS PAGE

    Insufficient permission to use the Cloud KMS key The cloudkms.cryptoKeyEncrypterDecrypter role is missing on the user or service account you are using to run operations on Cloud SQL instances, or the Cloud KMS key version doesn't exist. Add the cloudkms.cryptoKeyEncrypterDecrypter role on your user or service account.

    GO TO THE IAM ACCOUNTS PAGE


    If the role is already on your account, see Creating a key to learn how to create a new key version. See note.
    Cloud KMS key is not found The key version does not exist. Create a new key version. See Creating a key. See note.
    Cloud SQL instance and Cloud KMS key version are in different regions The Cloud KMS key version and Cloud SQL instance must be in the same region. It does not work if the Cloud KMS key version is in a global region or multi-region. Create a key version in the same region where you want to create instances. See Creating a key. See note.