terrymanu commented on issue #35054:
URL:
https://github.com/apache/shardingsphere/issues/35054#issuecomment-3506365698
Issue Analysis
I understand you want to implement read-write separation in ShardingSphere
5.5.0 with a specific requirement:
- All read requests should default to the primary database
- Only specific SQL queries should be directed to the secondary database
This is not a bug but a configuration requirement. ShardingSphere supports
this use case through several approaches.
Recommended Solutions
Solution 1: Hint-based Routing (Recommended)
Use Hint manager to force route queries to the primary database:
// For specific queries that should go to secondary database
try (HintManager hintManager = HintManager.getInstance()) {
hintManager.setWriteRouteOnly(); // Force route to primary
// Execute your query that should go to primary
jdbcTemplate.query("SELECT * FROM table_name", rowMapper);
}
// For regular queries (remove hint to use default routing)
try (HintManager hintManager = HintManager.getInstance()) {
hintManager.setReadRouteOnly(); // Force route to secondary
// Execute specific queries that should go to secondary
jdbcTemplate.query("SELECT * FROM table_name WHERE condition",
rowMapper);
}
Solution 2: Load Balance Configuration
Configure your read data sources with minimal weight to minimize secondary
database usage:
dataSources:
primary_ds:
# Your primary database configuration
secondary_ds:
# Your secondary database configuration
readWriteSplitting:
dataSources:
read_write_ds:
writeDataSourceName: primary_ds
readDataSourceNames:
- secondary_ds
loadBalancerName: round_robin
loadBalancers:
round_robin:
type: ROUND_ROBIN
props:
# Set minimal weight for secondary
secondary_ds: "1"
Solution 3: Custom SQL Hint (Most Flexible)
Use SQL hints to control routing for specific queries:
-- Force route to primary database
/* SHARDINGSPHERE_HINT: WRITE_ROUTE_ONLY */
SELECT * FROM table_name;
-- Force route to secondary database
/* SHARDINGSPHERE_HINT: READ_ROUTE_ONLY */
SELECT * FROM table_name WHERE specific_condition;
Questions for Better Assistance
To provide the most suitable solution, I need more information:
1. Business Scenario: Why do you need read requests to default to the
primary database? Is it for data consistency, performance, or other reasons?
2. Specific SQL Definition: What defines the "specific SQL queries" that
should go to the secondary database? Is it based on:
- Table names?
- SQL conditions?
- Query complexity?
- Time sensitivity?
3. Current Configuration: Do you already have a read-write separation
configuration in place?
4. Usage Mode: Are you using ShardingSphere-Proxy or ShardingSphere-JDBC?
5. Database Setup: What is your primary/secondary database configuration?
Recommendation
Based on typical use cases, I recommend Solution 1 (Hint-based Routing) as
it provides:
- Fine-grained control over query routing
- Easy to implement and maintain
- Clear separation of routing logic
- No complex configuration changes
Would you like me to provide a more detailed configuration example based
on your specific requirements?
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