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asmhatre 448c383879 Add jdbc-vs-jpa module: Spring Data JDBC vs JPA on a shared Order aggregate

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.

2026-09-17 19:09:35 +00:00

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jdbc-vs-jpa

Companion code for Spring Data JDBC vs Spring Data JPA in 2026: When Dropping the ORM Is the Right Call on ankurm.com.

The same Customer → Order → OrderItem domain, modelled twice — once with Hibernate/Spring Data JPA (com.ankurm.jdbcvsjpa.jpa), once with Spring Data JDBC (com.ankurm.jdbcvsjpa.jdbc) — running against the same H2 database through the same StatementLoggingDataSource, so every SQL-statement count quoted in the article is a fair, apples-to-apples measurement, not two separate benchmarks run under different conditions.

Tested with: Spring Boot 4.1.1 / Spring Framework 7.0.9 / Spring Data JDBC 4.1.1 / Spring Data JPA (Hibernate ORM) via the Boot 4.1.1 BOM / H2 2.x / JDK 25 (Temurin 25.0.4.1).

Quickstart

./mvnw test                 # runs everything, regenerates docs/output/
./mvnw spring-boot:run       # then: curl localhost:8080/diag/sql-log

Where things are


Shared domain	docs/01-the-shared-domain.md
JPA side	docs/02-the-jpa-side.md — `src/main/java/.../jpa/`
The SQL log mechanism	docs/03-the-sql-log.md — `src/main/java/.../support/`
JDBC side	docs/04-the-jdbc-side.md — `src/main/java/.../jdbc/`
The aggregate boundary	docs/05-the-aggregate-boundary.md
Production checklist	docs/06-when-this-gets-expensive.md

Captured output

Every number quoted in the article is one of these files, regenerated by ./mvnw test:

File	What it shows
docs/output/00-statement-count-comparison.txt	The headline table: statement counts, JPA vs JDBC, across order/item counts
docs/output/01-lazy-outside-session.txt	`LazyInitializationException` triggered for real
docs/output/02-n-plus-one.txt	N+1 from a plain `findAll()` + loop
docs/output/03-entity-graph-fixed-cost.txt	`@EntityGraph` flattening the cost to a constant
docs/output/04-dirty-checking-autoflush.txt	An UPDATE with no `save()` call anywhere
docs/output/05-orphan-removal-delete.txt	`orphanRemoval` turning a list removal into a DELETE
docs/output/06-fixed-cost-load.txt	Spring Data JDBC's fixed-statement-count `findById`
docs/output/07-delete-then-insert.txt	The delete-then-batched-insert collection replace
docs/output/08-aggregate-reference-no-join.txt	`AggregateReference` costing zero extra statements
docs/output/09-optimistic-locking.txt	`@Version` conflict on both stacks
docs/output/10-list-order-key-column.txt	`keyColumn` making list order deterministic

Diagnostic endpoint

GET /diag/sql-log dumps every statement executed in this JVM since the last reset — the same mechanism the tests use. Delete DiagController before shipping; it is a demo aid, not a feature.

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