This topic describes the causes, impacts, and solutions of query statements that are executed for a long time in apsaradb RDS for MySQL.


Background information

Alibaba Cloud reminds you that:

  • When you perform operations that have risks, such as modifying instance configurations or data, check the disaster recovery and fault tolerance capabilities of the instances to ensure data security.
  • Before you modify the configurations and data of instances including but not limited to ECS and RDS instances, we recommend that you create snapshots or enable RDS log backup.
  • If you have authorized or submitted security information such as the logon account and password in the Alibaba Cloud Management console, we recommend that you modify such information in a timely manner.

The following section describes how to use apsaradb RDS for MySQL to manage long-time queries.



During the use of RDS MySQL, queries with long running time may occur due to some reasons, such as SQL injection, poor SQL execution efficiency, or DDL statement-triggered Lock wait.

Instructions for more information about how to wait for the metadata lock, see resolves the problem that metadata locks cause database operations to fail.

  • Time-consuming queries caused by inefficient SQL statements
  • A query lasting for a long time due to SQL injection.
  • Table metadata Lock wait caused by DDL statement.


Problems caused by long-time queries

Generally speaking, query over a long period unless it is a BI or report query it is meaningless for applications and consumes system resources. For example, many long-term queries may cause problems such as excessive CPU, IOPS, and connections, resulting in system instability.


How to avoid long-time query execution

To avoid long query execution, see the following examples.

  • You must take protective measures against SQL injection to your applications.
  • Perform a stress test before the release of the new feature module to avoid the heavy load of SQL statements with poor execution efficiency.
  • Try to create and delete indexes, modify table schemas, and maintain tables during off-peak hours.


How to handle queries that are executed for a long time

Please refer resolves the problem that metadata locks cause database operations to fail.


Application scope

  • ApsaraDB RDS for MySQL