asmhatre
448c383879
Same Customer/Order/OrderItem domain modelled with Hibernate/Spring Data JPA and Spring Data JDBC side by side, both running through a shared StatementLoggingDataSource so SQL-statement counts are directly comparable. 11 tests, 11 captured transcripts, 6 doc chapters. Companion repo for the ankurm.com article on when to drop the ORM.
2.7 KiB
01 — The shared domain
← README · next: the JPA side →
Both stacks in this module model the same thing: a Customer who places Orders, each with a
list of OrderItems. It is deliberately the smallest domain that has everything worth arguing
about — a one-to-many collection, a reference to a second aggregate, and a field a reader will
want to mutate in place.
| Concept | JPA package (com.ankurm.jdbcvsjpa.jpa) |
JDBC package (com.ankurm.jdbcvsjpa.jdbc) |
|---|---|---|
| Table prefix | jpa_* |
JDBC_* (see the identifier-casing note below) |
| Order → Customer | @ManyToOne(fetch = LAZY) object reference |
AggregateReference<Customer, Long> — a typed foreign key, never a loaded object |
| Order → items | @OneToMany(mappedBy, cascade = ALL, orphanRemoval = true), List<OrderItem> |
@MappedCollection(idColumn, keyColumn), List<OrderItem> |
| Identity of a child row | @ManyToOne back-reference to its parent |
none — a JDBC OrderItem has no idea which Order owns it |
| Optimistic locking | @Version Long version |
@Version Long version (same annotation, same package: org.springframework.data.annotation) |
Both sides run against the same H2 database through the same
StatementLoggingDataSource
— see 03 — the SQL log for why that matters for the numbers in the article.
A casing trap that cost a debugging session
Spring Data JDBC treats an explicit @Table("some_name") or @Column("some_name") value as a
literal, quoted SQL identifier — it is rendered exactly as given, in double quotes. Properties
with no explicit annotation go through the H2 dialect's default identifier processing instead,
which upper-cases them. H2 itself upper-cases any unquoted identifier in DDL. The result: an
unquoted create table jdbc_customer(...) in schema.sql produces a table H2 privately calls
JDBC_CUSTOMER, but @Table("jdbc_customer") generates INSERT INTO "jdbc_customer" (...) —
quoted, lower-case, and therefore a different identifier as far as H2 is concerned. The fix used
throughout this module is to give every explicit @Table/@Column/@MappedCollection value in
upper case, matching H2's own folding, so the literal and the folded name agree. See
jdbc/Order.java for the annotations
and schema.sql for the DDL. This is exactly the kind of
thing that never shows up in a tutorial that only ever runs one save and eyeballs the console.
Continue to 02 — the JPA side.