r2dbc: Spring Data R2DBC CRUD, DatabaseClient, reactive transactions and Testcontainers Postgres (post 2)

Co-Authored-By: Claude Sonnet 5.5 <[email protected]>
Claude-Session: https://claude.ai/code/session_017ic4b4VQVEJWetTT1dYzyJ

r2dbc/README.md

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+# r2dbc
+
+Companion code for the ankurm.com post
+[Reactive Data Access with Spring Data R2DBC: CRUD, Transactions and When to Choose It](https://ankurm.com/spring-data-r2dbc-crud-transactions/).
+
+Spring Boot 4.1.2, JDK 25, Spring Data R2DBC, r2dbc-postgresql 1.1.3.RELEASE, PostgreSQL 17 (Testcontainers 2.0.5).
+
+## What is in here
+
+- `Customer`, `PurchaseOrder`, `Account`: plain records, one row each. No relationship mapping.
+- `CustomerRepository`: `ReactiveCrudRepository`, derived queries, `@Query`, `@Modifying`.
+- `CustomerOrderService`: three ways to load customers with orders (1+N, two queries, one JOIN with `DatabaseClient`).
+- `AccountService`: `@Transactional` and `TransactionalOperator`, with rollback on error.
+- `schema.sql`: run by Spring Boot through the R2DBC connection at startup.
+- Tests use `StepVerifier` and write the transcripts in `output/`.
+
+## Run
+
+```bash
+cd r2dbc
+./scripts/run-all.sh      # needs Docker; regenerates output/*.txt
+```
+
+`output/07-throughput-indicative.txt` is an indicative JDBC vs R2DBC run on a shared 2-vCPU sandbox.
+Treat it as a harness, not a result: run it on your own hardware.