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- What's New
- Service Overview
- Getting Started
-
User Guide
- Function Overview
- Permissions Management
-
Instance Management
- Buying a DDM Instance
- Splitting Read-only and Read-Write Services
- Changing Class of a DDM Node
- Scaling Out a DDM Instance
- Scaling In a DDM Instance
- Changing Billing Mode of a DDM Instance
- Renewing a DDM Instance
- Restarting a DDM Instance
- Unsubscribing from a DDM Instance
- Deleting a DDM Instance
- Modifying Parameters of a DDM Instance
- Splitting Read and Write Requests
- Configuring a Parameter Template
- Connection Management
-
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
- Shard Configuration
- Data Node Management
- Account Management
- Backups and Restorations
-
Data Migration
- Overview
- Migration Evaluation
- Scenario 1: Migrating Data from Huawei Cloud RDS to DDM
- Scenario 2: Migrating Data from an On-Premises RDS Instance for MySQL to DDM
- Scenario 3: Migrating Data from a Third-Party RDS for MySQL Instance to DDM
- Scenario 4: Migrating Data from a Self-Built MySQL Instance to DDM
- Scenario 5: Migrating Data from Heterogeneous Databases to DDM
- Scenario 6: Exporting Data from a DDM Instance
- Slow Queries
- Monitoring Management
- Auditing
-
SQL Syntax
- Introduction
- DDL
- DML
- Functions
- Use Constraints
- Supported SQL Statements
- Global Sequence
- Database Management Syntax
- Advanced SQL Functions
- Quotas
- Change History
-
API Reference
- Before You Start
- API Overview
- Calling APIs
-
APIs (Recommended)
-
DDM Instances
- Buying a DDM instance
- Querying DDM Instances
- Querying 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 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
- Querying DDM Engine Information
- Querying DDM Node Classes Available in an AZ
- Changing the Node Class of a DDM Instance
- Schemas
- DDM Accounts
- Monitoring
-
DDM Instances
- APIs (Unavailable Soon)
- Appendix
- Change History
- SDK Reference
-
Best Practices
- Overview
- Formulating Sharding Rules
- Determining the Number of Shards in a Schema
- Using Broadcast and Unsharded Tables
- Transaction Models
- SQL Standards
- Migrating an Entire RDS Database to DDM
- Migrating an Entire MyCat Database to DDM
- Accessing DDM Using a JDBC Connection Pool
- Logging In to a DDM Instance Using Navicat
- Migrating Data from RDS for MySQL to DDM Using DRS
- Performance White Paper
-
FAQs
- General Questions
-
DDM Usage
- How Does DDM Perform Sharding?
- What Do I Do If I Fail to Connect to a DDM Instance Using the JDBC Driver?
- What Version and Parameters Should I Select?
- Why It Takes So Long Time to Export Data from MySQL Using mysqldump?
- What Do I Do If a Duplicate Primary Key Error Occurs When Data Is Imported into DDM?
- 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
- RDS-related Questions
- Connection Management
- Resource Freezing, Release, Deletion, and Unsubscription
- Change History
- Videos
Show all
SHOW RULE
Command Format:
show rule: used to view the sharding rule of each logical table in a certain schema. show rule from table_name: displays the sharding rule of a specified logical table in a certain schema.
Command Output:
The following is an example output of show rule.
The following is an example output of show rule from table_name.
Output Details:
TABLE_NAME: indicates the name of the logical table.
BROADCAST: specifies whether the table is a broadcast table. 0 indicates that the table is not a broadcast table. 1 indicates the table is a broadcast table.
DB_PARTITION_KEY: indicates the database sharding key. Leave this field blank if database sharding is not required.
DB_PARTITION_POLICY: indicates the database sharding algorithm. The value can be HASH, YYYYMM, YYYYDD, and YYYYWEEK.
DB_PARTITION_COUNT: indicates the number of database shards.
DB_PARTITION_OFFSET: indicates where a new database shard starts from.
PARTITION_RANGE: indicates the sharding range when the database sharding algorithm is range.
TB_PARTITION_KEY: indicates the table sharding key. Leave this field blank if table sharding is not required.
TB_PARTITION_POLICY: indicates the table sharding algorithm. The value can be HASH, MM, DD, MMDD, or WEEK.
TB_PARTITION_COUNT: indicates the number of physical tables in each database shard.
TB_PARTITION_OFFSET: indicates where a new physical table starts from.
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