Snippet

Dynamic Multi-Tenancy Routing with AbstractRoutingDataSource

This expert-level pattern allows a Spring application to switch between multiple data sources at runtime based on a lookup key (e.g., a Tenant ID from a ThreadLocal). It is essential for SaaS architectures where data isolation is required at the database level.

snippet.java

java

public class TenantRoutingDataSource extends AbstractRoutingDataSource {
    @Override
    protected Object determineCurrentLookupKey() {
        return TenantContext.getCurrentTenant();
    }
}
 
@Configuration
public class DataSourceConfig {
    @Bean
    public DataSource dataSource() {
        TenantRoutingDataSource routingDataSource = new TenantRoutingDataSource();
        Map<Object, Object> targetDataSources = new HashMap<>();
        targetDataSources.put("TENANT_A", tenantADataSource());
        targetDataSources.put("TENANT_B", tenantBDataSource());
        routingDataSource.setTargetDataSources(targetDataSources);
        routingDataSource.setDefaultTargetDataSource(defaultDataSource());
        return routingDataSource;
    }
}

spring

Breakdown

extends AbstractRoutingDataSource

Inherits from Spring's internal routing mechanism for dynamic data source resolution.

determineCurrentLookupKey()

The core logic that Spring calls before every query to decide which database to use.

setTargetDataSources(targetDataSources)

Registers a map of available data sources associated with their respective lookup keys.

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Dynamic Multi-Tenancy Routing with AbstractRoutingDataSource

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