- What's New
- Function Overview
- Service Overview
- Billing
- Getting Started
-
User Guide
- Permissions Management
- Logging in to a DB Instance
-
MySQL
- Account Management
- Database Management
- SQL Operations
- Table Management
- View Management
- Stored Procedure Management
- Event Management
- Trigger Management
- Function Management
- Data Import and Export
- Data Generator (Not Promoted)
- Tracking and Rolling Back Data (Not Promoted)
- Task Management
- Table Structure Comparison and Synchronization (Not Promoted)
- Intelligent O&M (New Version)
- Intelligent O&M (Old Version)
- RDS for SQL Server
- PostgreSQL
-
RDS for MariaDB
- Account Management
- Database Management
- SQL Operations
- Table Management
- View Management
- Stored Procedure Management
- Event Management
- Trigger Management
- Function Management
- Data Import and Export
- Data Generator (Not Promoted)
- Task Management
- Table Structure Comparison and Synchronization (Not Promoted)
- Intelligent O&M
- GaussDB
-
TaurusDB
- Account Management
- Database Management
- SQL Operations
- Table Management
- View Management
- Event Management
- Stored Procedure Management
- Function Management
- Trigger Management
- Data Import and Export
- Data Generator (Not Promoted)
- Task Management
- Table Structure Comparison and Synchronization (Not Promoted)
- Intelligent O&M
- GeminiDB Cassandra
- GaussDB(DWS) (Unavailable Soon)
- DDS
- DDM
- Audit
- Event Monitoring
- Best Practices
-
API Reference
- Before You Start
- API Overview
- Calling APIs
-
APIs (in OBT)
- API Version Queries
-
Cloud DBA
- Registering a Database User
- Modifying a Database User
- Deleting a Database User
- Querying Intelligent O&M Quotas
- Querying Database User Information
- Querying Database Users
- Killing Sessions
- Querying the SQL Execution Plan (GET Request)
- Querying the SQL Execution Plan (POST Request)
- Querying Metadata Locks
- Querying Instance Sessions
- Querying InnoDB Lock Waits
- Enabling or Disabling SQL Explorer and Slow Query Log
- Querying Whether SQL Explorer and Slow Query Log Are Enabled
- Exporting Slow Query Logs
- Exporting SQL Explorer Data
- Querying Whether SQL Statement Concurrency Control Is Enabled
- Enabling or Disabling SQL Statement Concurrency Control
- Querying Concurrency Control Rules of SQL Statements
- Generate Keywords of a Concurrency Control Rule from the Original SQL Statement
- Creating a Concurrency Control Rule for SQL Statements
- Deleting a Concurrency Control Rule of SQL Statements
- Querying SQL Statement Concurrency Control Tasks
- Exporting the Top SQL Template List
- Exporting SQL Execution Time Distribution
- Exporting the Slow SQL Template List
- Viewing the Instance List on the Intelligent O&M Page
- Setting a Shared Link
- Deleting a Shared Link
- Executing a SQL Diagnosis
- Obtaining Diagnosis Results
- Creating an Instance Diagnosis Task
- Querying Instance Diagnosis Reports
- Obtaining an Instance Diagnosis Report
- Synchronizing the Instance List
- Deprecated APIs
- Permissions Policies and Supported Actions
- Appendixes
-
FAQs
-
Product Consulting
- How Is DAS Billed?
- Which Data Sources Does DAS Support?
- Does DAS Support Multi-Region Access?
- Where Is SQL Execution Records Saved If I Enable This Function?
- What Should I Enter in the Database Column to Log In to a PostgreSQL DB Instance on the DAS Console?
- Will I Be Changed If I Enable Collect Metadata Periodically and Show Executed SQL Statements on the Add Login Page?
-
Managing connections
- What Should I Do If I Can't Connect to My DB Instance Due to Insufficient Permissions?
- What Should I Do If I Can't Connect to My RDS for MySQL Instance?
- What Should I Do If I Can't Connect to My ECS (MySQL) Instance?
- What Should I Do If I Can't Connect to My RDS for SQL Server Instance?
- What Should I Do If I Can't Connect to My ECS (Microsoft SQL Server) Instance?
- What Should I Do If I Can't Connect to My RDS for PostgreSQL Instance?
- What Should I Do If I Can't Connect to My ECS (PostgreSQL) Instance?
- What Should I Do If I Can't Connect to My DDS Instance?
- What Should I Do If I Can't Connect to My GaussDB(for MySQL) Instance?
- What Should I Do If I Can't Connect to My GaussDB Instance?
- What Should I Do If I Can't Connect to My DDM Instance?
- How Do I View and Modify ECS Security Group Rules?
- How Do I View and Modify Firewall Rules?
- What Should I Do If My Connection Fails?
-
Usage
- What Can I Do If Garbled Characters Are Displayed in the Exported Database Result Set?
- What Are the Precautions for Connecting DAS to a Third-Party Client?
- What Are the Username and Password for DAS?
- What Should I Do If Table Obtaining Times Out?
- How Do I Modify the Collation?
- When a user creates a data tracking task, an error message indicating that the current user does not have the OBS operator permissions is displayed.
- Resource Freezing, Release, Deletion, and Unsubscription
-
Product Consulting
- Glossary
- Videos
-
More Documents
-
User Guide (ME-Abu Dhabi Region)
- Service Overview
- Getting Started
-
User Guide
- Permissions Management
- Logging In to the DAS Console
- Adding Login Information
- Modifying Login Information
- Deleting Login Information
- Logging In to Databases Shared by Others
- MySQL DB Instance Management (Development Tool)
- Microsoft SQL Server DB Instance Management (Development Tool)
- PostgreSQL DB Instance Management (Development Tool)
- DDS DB Instance Management (Development Tool)
- Enterprise Change Approval
- Intelligent O&M
- FAQs
- Change History
-
User Guide (Kuala Lumpur Region)
- Service Overview
- Getting Started
-
User Guide
- Permissions Management
- Logging in to a DB Instance
-
MySQL
- Account Management
- Database Management
- SQL Operations
- Table Management
- View Management
- Stored Procedure Management
- Event Management
- Trigger Management
- Function Management
- Data Import and Export
- Data Generator (Not Promoted)
- Tracking and Rolling Back Data (Not Promoted)
- Task Management
- Table Structure Comparison and Synchronization (Not Promoted)
- Intelligent O&M (New Version)
- Intelligent O&M
- RDS for SQL Server
- PostgreSQL
- DDS
- DDM
- Audit
-
FAQs
-
Managing connections
- What Should I Do If I Can't Connect to My RDS for MySQL Instance?
- What Should I Do If I Can't Connect to My ECS (MySQL) Instance?
- What Should I Do If I Can't Connect to My RDS for PostgreSQL Instance?
- What Should I Do If I Can't Connect to My ECS (PostgreSQL) Instance?
- What Should I Do If I Can't Connect to My DDS Instance?
- What Can I Do If a GaussDB(for MySQL) Instance Fails to Be Connected?
- What Should I Do If I Can't Connect to My GaussDB Instance?
- What Should I Do If I Can't Connect to My DDM Instance?
- How Do I View and Modify ECS Security Group Rules?
- How Do I View and Modify Firewall Rules?
- What Should I Do If My Connection Fails?
- Usage
-
Managing connections
- Change History
-
User Guide (ME-Abu Dhabi Region)
- General Reference
Show all
Copied.
SQL Statement Concurrency Control
Concurrency Control restricts the execution of SQL statements based on specified rules when there are SQL statements that cannot be optimized timely or a resource (for example, vCPU) bottleneck occurs.
Usage Notes
- The kernel version of primary RDS for MySQL instances must be 5.6.50.3, 5.7.31.4, 8.0.25.1, or later.
- The kernel version of RDS for MySQL read replicas must be 5.6.51.6, 5.7.37.1, 8.0.25.1, or later.
- Separate concurrency rules can be added for RDS for MySQL read replicas of the kernel version 5.7.38-221000 or later.
- If a SQL statement matches multiple concurrency control rules, only the latest rule takes effect.
- Keywords in a concurrency control rule are sorted in a specific order, and the system will match them from first to last. For example, if one rule contains the keyword a~and~b, the system only matches xxx a>1 and b>2.
- If the replication delay is too long, adding or deleting a concurrency control rule for a read replica does not take effect immediately.
- If you replicate data from an instance to a third-party instance based on binlogs, deleting or adding SQL statement concurrency rules from or to the instance will interrupt the replication process.
- Each SQL statement concurrency control rule can contain a maximum of 128 keywords.
- Currently, SQL Statement Concurrency Control supports only keywords SELECT, UPDATE, and DELETE.
- Empty characters before and after each keyword will be ignored, for example, spaces, \n, \r, and \t.
- Too many keywords or rules may affect performance. Retain only required concurrency control rules.
- Up to 100 concurrency control rules can be retained.
- If a SQL statement has been stored in query cache, it is not subject to concurrency control.
- SQL statement concurrency control does not limit concurrency for:
- System tables
- SQL statements used to query data, for example, select sleep(xxx)
- User root in versions including 5.6, 5.7.41.230700 and earlier versions in 5.7, and 8.0.28.230701 and earlier versions in 8.0
- Stored procedures, triggers, and functions
Procedure
- Log in to the Huawei Cloud console.
- Click
in the upper left corner and select a region and project.
- Click
in the upper left corner, and under Databases, click Data Admin Service.
- In the navigation pane, choose Intelligent O&M > Instance List.
Alternatively, on the Overview page, click Go to Intelligent O&M.
- In the upper right corner of the Instance List page, search for instances by engine type, instance name, or instance IP.
Figure 1 Searching for instances
- Locate the target instance and click Details.
- In the upper right corner of the page, click Go to Old Edition.
- Choose SQL > SQL Statement Concurrency Control.
- On the displayed page, toggle on Concurrency Control.
- Click View Supported Versions.
Figure 2 Viewing version constraints
- Click Add Concurrency Control Rule. In the displayed dialog box, select a SQL statement type, enter keywords, and specify the maximum number of concurrent SQL statements.
- Keyword: You can enter keywords or copy an existing SQL statement to the text box and click Generate Keyword.
NOTE:
- Keywords generated from an original SQL statement are only for reference.
- Each SQL statement concurrency control rule can contain a maximum of 128 keywords.
The following explains how a rule matches SQL statements based on keywords:
For example, if you enter the keywords select~id~name~from~t3~where~age~>~27 (the keywords are separated by a tilde (~)) for a rule, the system will match them from first to last and restrict the execution of any SQL statement that contains these keywords.
- Max. Concurrency: SQL statements that meet the specified SQL type and keywords and exceed the value of Max. Concurrency will not be executed.
NOTE:
SQL statements that have been executed before a concurrency control rule is added are not counted.
If you add a concurrency control rule and set Max. Concurrency to 0, the concurrency of the following SQL statements will be controlled:
"select id, name from t3 where age > 27" "select id, name, age from t3 where age > 27" "select id, name from t3 where age > 5 and id < 27"
But the concurrency of the following SQL statement will not be controlled:
"select name, age from t3 where age > 27"
- Keyword: You can enter keywords or copy an existing SQL statement to the text box and click Generate Keyword.
- Confirm the settings and click OK.
If a SQL statement concurrency control rule is no longer needed, click Delete in the Operation column.
Feedback
Was this page helpful?
Provide feedbackThank you very much for your feedback. We will continue working to improve the documentation.See the reply and handling status in My Cloud VOC.
For any further questions, feel free to contact us through the chatbot.
Chatbot