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Data Migration
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DDM Instances
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- Deleting a DDM Instance
- Restarting a DDM Instance
- Reloading Table Data
- Scaling Out a DDM Instance
- Scaling in a DDM instance
- Modifying the Read Policy of the Associated DB Instance
- Synchronizing Data Node Information
- Querying Nodes of a DDM Instance
- Querying Details of a DDM Instance Node
- Querying Parameters of a Specified DDM Instance
- Modifying Parameters of a DDM Instance
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DDM Instances
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- Accessing DDM Using a JDBC Connection Pool
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- Sharding Database and Table Data of an RDS for MySQL Instance
- Performance White Paper
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FAQs
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- How Does DDM Perform Sharding?
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- What Should I Do If an Error Message Is Returned When I Specify an Auto-Increment Primary Key During Migration?
- What Do I Do If an Error Is Reported When Parameter Configuration Does Not Time Out?
- Which Should I Delete First, a Schema or its Associated RDS Instances?
- Can I Manually Delete Databases and Accounts Remained in Data Nodes After a Schema Is Deleted?
- SQL Syntax
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RDS-related Questions
- Is the Name of a Database Table Case-Sensitive?
- What Risky Operations on RDS for MySQL Will Affect DDM?
- How Do I Handle Data with Duplicate Primary Keys in a Table?
- How Can I Query RDS for MySQL Information by Running Command show full innodb status?
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More Documents
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User Guide (ME-Abu Dhabi Region)
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Parameter Template Management
- Creating a Parameter Template
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- Comparing Two Parameter Templates
- Viewing Parameter Change History
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- Applying a Parameter Template
- Viewing Application Records of a Parameter Template
- Modifying the Description of a Parameter Template
- Deleting a Parameter Template
- Task Center
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SQL Syntax
- Introduction
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- Unsupported Items
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- Global Sequence
- Database Management Syntax
- Advanced SQL Functions
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FAQs
- General Questions
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DDM Usage
- How Can I Rectify a Fault in Accessing DDM by Using the JDBC Driver?
- What Version and Parameters Should I Select?
- Why It Takes So Long Time to Export Data from MySQL Using mysqldump?
- How Should I Handle the Duplicate Primary Key Error Occurring After Data Is Imported into DDM?
- What Should I Do If an Error Message Is Returned After I Specify an Auto-Increment Primary Key?
- How Do I Handle the Error Reported When Parameter Configuration Does Not Time Out?
- Which Should I Delete First, Schema or Associated RDS DB Instances?
- Should I Manually Delete Databases and Accounts Remained in the Associated RDS DB Instances After a Schema Is Deleted?
- SQL Syntax
- RDS-related Questions
- Connection Management
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User Guide (Kuala Lumpur Region)
- Service Overview
- Getting Started
- Function Overview
- Instance Management
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Parameter Template Management
- Creating a Parameter Template
- Editing a Parameter Template
- Comparing Two Parameter Templates
- Viewing Parameter Change History
- Replicating a Parameter Template
- Applying a Parameter Template
- Viewing Application Records of a Parameter Template
- Modifying the Description of a Parameter Template
- Deleting a Parameter Template
- Task Center
- Schema Management
- Account Management
- Backup Management
- Monitoring Management
- Auditing
-
SQL Syntax
- Introduction
- DDL
- DML
- Functions
- Unsupported Items
- Supported SQL Statements
- Global Sequence
- Database Management Syntax
- Advanced SQL Functions
-
FAQs
- General Questions
-
DDM Usage
- How Can I Rectify a Fault in Accessing DDM by Using the JDBC Driver?
- What Version and Parameters Should I Select?
- Why It Takes So Long Time to Export Data from MySQL Using mysqldump?
- How Should I Handle the Duplicate Primary Key Error Occurring After Data Is Imported into DDM?
- What Should I Do If an Error Message Is Returned After I Specify an Auto-Increment Primary Key?
- How Do I Handle the Error Reported When Parameter Configuration Does Not Time Out?
- Which Should I Delete First, Schema or Associated RDS DB Instances?
- Should I Manually Delete Databases and Accounts Remained in the Associated RDS DB Instances After a Schema Is Deleted?
- SQL Syntax
- RDS-related Questions
- Connection Management
-
API Reference (Kuala Lumpur Region)
- Before You Start
- API Overview
- Calling APIs
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DDM Instance Management
- Querying DDM Engine
- Querying the Quota of Classes Available in Each AZ
- Creating a DDM Instance
- Querying DDM Instances
- Viewing Details of a DDM Instance
- Modifying the Name of a DDM Instance
- Modifying the Security Group of a DDM Instance
- Deleting a DDM Instance
- Restarting a DDM Instance
- Reloading Table Data
- Scaling Out a DDM instance
- Scaling In a DDM instance
- Modifying the Read Policy of the Associated DB Instance
- Synchronizing DB Instance Data
- Querying Nodes of a DDM Instance
- Querying Details of a DDM Instance Node
- Querying Parameters of a Specified DDM Instance
- Modifying Parameters of a DDM Instance
- Schema Management
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- Monitoring Management
- Permissions Policies and Supported Actions
- Appendix
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User Guide (ME-Abu Dhabi Region)
- General Reference
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Configuring Read Weights
This section describes how to adjust read/write weights of a primary instance and its read replicas. If one DDM instance is associated with multiple data nodes, you can configure read weights of the data nodes in batches.
Precautions
If a data node (associated DB instance) has no read replicas, you cannot configure a read/write weight for it.
Batch Configuring Read Weights for Multiple DB Instances
- Log in to the DDM console.
- On the Instances page, locate the DDM instance whose associated DB instances you want to configure read weights for.
- Click the instance name and go to the Basic Information page.
- In the navigation pane on the left, choose Data Nodes and click Configure Read Weight.
Figure 1 Data Nodes
- Configure read weights for DB instances associated with the DDM instance
In the displayed dialog box, you can click Synchronize to apply the read weight of the first DB instance to other instances. This operation requires that each of the DB instances has the same number of read replicas.
Otherwise, you need to manually configure the read weight for each DB instance.
- The read weight can be 0 to 100.
- Read replicas of one of the DB instance handle all separated read requests by default. To re-assign read/write requests, you can configure read weights of the instance and its read replicas.
- After the read weights are configured, the primary instance and its read replica will handle read requests according to the following formulas:
- Primary instance: Read weight of primary instance/Total read weights of primary instance and read replica
- Read replica: Read weight of read replica/Total read weights of primary instance and read replica
For example, if an RDS for MySQL instance contains one primary instance and one read replica and read weights of the primary instance and its read replica are 20 and 80 respectively, they will process read requests in the ratio of 1:4. In other words, the primary instance processes 1/4 of read requests and the read replica processes 3/4. Write requests are automatically routed to the primary instance.
- After the read weight is configured, you can view the updated read weight in the data node list.
Configuring the Read Weight for a Single DB Instance
- Log in to the DDM console.
- On the Instances page, locate the DDM instance whose associated DB instance you want to configure a read weight for.
- Click the instance name and go to the Basic Information page.
- In the navigation pane on the left, choose Data Nodes.
- Locate the required instance and click Configure Read Weight in the Operation column.
Figure 2 Configuring the read weight for a single DB instance
- The read weight can be 0 to 100.
- Read replicas of one of the DB instance handle all separated read requests by default. To re-assign read/write requests, you can configure read weights of the instance and its read replicas.
- After the read weights are configured, the primary instance and its read replica will handle read requests according to the following formulas:
- Primary instance: Read weight of primary instance/Total read weights of primary instance and read replica
- Read replica: Read weight of read replica/Total read weights of primary instance and read replica
For example, if an RDS for MySQL instance contains one primary instance and one read replica and read weights of the primary instance and its read replica are 20 and 80 respectively, they will process read requests in the ratio of 1:4. In other words, the primary instance processes 1/4 of read requests and the read replica processes 3/4. Write requests are automatically routed to the primary instance.
- After the read weight is configured, you can view the updated read weight in the data node list.
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