Data Modeling Best Practices for SAP HANA Express and Spring Boot

August 31, 2025

This guide explains best practices for data modeling when using SAP HANA Express with Spring Boot. The focus is on clean design and easy integration.

1. Use Proper Naming Conventions

Use singular table names (User, Order, not Users, Orders).
Use lowercase with underscores for columns (first_name, created_at).
Keep consistency across HANA tables and Java entities.

2. Define Primary Keys Clearly

Always define a primary key:

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;

In SAP HANA, use integer or bigint as ID for performance.

3. Normalize Where Needed, Denormalize Where Useful

Normalization: avoid redundant data for core models (like User, Product).
Denormalization: for reporting tables or analytics, store computed values.

4. Use Proper Data Types

Map HANA NVARCHAR to Java String.
Map HANA DECIMAL to Java BigDecimal.
Avoid oversized columns — size impacts memory in HANA.

5. Leverage JPA Relationships

Use JPA mappings to model relations:

@OneToMany(mappedBy = "user")
private List<Order> orders;

@ManyToOne
@JoinColumn(name = "user_id")
private User user;

Keep relationships simple and avoid deeply nested mappings.

6. Add Indexes for Performance

In SAP HANA, create indexes for frequently queried fields:

CREATE INDEX IDX_USER_EMAIL ON USERS(EMAIL);

Also use @Column(unique = true) in entities when applicable.

7. Use DTOs for API Responses

Don’t expose entities directly. Use DTOs to send responses:

public record UserDTO(String name, String email) {}

Map entity to DTO in service layer.

8. Test with Sample Data

Seed data at startup to validate your model:

@Bean
CommandLineRunner init(UserRepository repo) {
    return args -> {
        repo.save(new User("Alice", "alice@email.com"));
        repo.save(new User("Bob", "bob@email.com"));
    };
}