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This guide shows how to build multi-tenant applications using Spring Boot and SAP HANA Express.

1. Define Tenant Context

Create a holder for the current tenant: 
public class TenantContext {
    private static final ThreadLocal<String> tenantId = new ThreadLocal<>();

    public static void setTenantId(String id) {
        tenantId.set(id);
    }

    public static String getTenantId() {
        return tenantId.get();
    }

    public static void clear() {
        tenantId.remove();
    }
}

2. Add Tenant Interceptor

Extract tenant ID from the request header: 
import jakarta.servlet.*;
import jakarta.servlet.http.HttpServletRequest;
import java.io.IOException;

public class TenantInterceptor implements Filter {
    @Override
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain chain)
            throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) req;
        String tenantId = request.getHeader("X-Tenant-ID");
        TenantContext.setTenantId(tenantId != null ? tenantId : "default");
        try {
            chain.doFilter(req, res);
        } finally {
            TenantContext.clear();
        }
    }
}
Register the filter in your config.

3. Configure Multi-Tenant Datasource

import org.hibernate.engine.jdbc.connections.spi.MultiTenantConnectionProvider;
import javax.sql.DataSource;
import java.sql.Connection;
import java.sql.SQLException;

public class TenantConnectionProvider implements MultiTenantConnectionProvider {
    private final DataSource dataSource;

    public TenantConnectionProvider(DataSource dataSource) {
        this.dataSource = dataSource;
    }

    @Override
    public Connection getConnection(String tenantId) throws SQLException {
        Connection conn = dataSource.getConnection();
        conn.setSchema(tenantId);
        return conn;
    }

    @Override
    public Connection getConnection() throws SQLException {
        return getConnection(TenantContext.getTenantId());
    }
}
Each tenant uses its own schema in SAP HANA Express.

4. Hibernate Multi-Tenant Configuration

import org.springframework.context.annotation.*;
import org.springframework.orm.jpa.*;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import javax.sql.DataSource;

@Configuration
public class HibernateConfig {
    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory(
            DataSource dataSource, TenantConnectionProvider connectionProvider) {
        LocalContainerEntityManagerFactoryBean emf = new LocalContainerEntityManagerFactoryBean();
        emf.setDataSource(dataSource);
        emf.setPackagesToScan("com.example.demo");
        emf.setJpaVendorAdapter(new HibernateJpaVendorAdapter());
        emf.getJpaPropertyMap().put("hibernate.multiTenancy", "SCHEMA");
        emf.getJpaPropertyMap().put("hibernate.multi_tenant_connection_provider", connectionProvider);
        return emf;
    }
}

5. Test Multi-Tenancy

  1. Create schemas in HANA: 
    CREATE SCHEMA tenant1;
CREATE SCHEMA tenant2;
  2. Insert different data in each schema.
  3. Call API with header X-Tenant-ID: tenant1 or tenant2 to switch tenants.

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