)]}' { "commit": "60d5342831ea3c20c4a3f166743af833421c169c", "tree": "7ca13e02cd8eb71c7fd5789a57dccb84a6294c57", "parents": [ "be10e162fa2735b9970ffbeb378c4cb0cc61d064" ], "author": { "name": "Andy Grove", "email": "agrove@apache.org", "time": "Wed May 13 15:52:05 2026 -0600" }, "committer": { "name": "GitHub", "email": "noreply@github.com", "time": "Wed May 13 15:52:05 2026 -0600" }, "message": "build: add examples module on a multi-module Maven build (#32)\n\n## Which issue does this PR close?\n\n- Closes #.\n\n## Rationale for this change\n\nThe repository lacks runnable end-to-end examples. Code snippets in the\ndocs are easy to drift out of sync with the API: there is no build step\nthat fails when a public method is renamed or removed.\n\nAdding an `examples/` Maven module that depends on the library lets the\nreactor compile every example on each build, so they cannot fall behind\nthe API. Doing this requires the repo to be a multi-module Maven\nproject; while we\u0027re there, the parent POM gets shared\n`dependencyManagement` and plugin versions so child modules stay terse.\n\n## What changes are included in this PR?\n\n**Multi-module restructure:**\n\n- Root `pom.xml` becomes the parent (`datafusion-java-parent`,\n`packaging\u003dpom`) with `dependencyManagement` for arrow, protobuf, junit,\nand the library itself.\n- `core/` is a new directory holding the existing library\n(`datafusion-java`). `src/` moves to `core/src/`.\n- `examples/` is a new module (`datafusion-java-examples`) depending on\nthe library via `${project.version}`. It wires `exec-maven-plugin` so\neach example launches with the right `java.library.path` and\n`--add-opens` flags.\n- `native/`, `proto/`, `Makefile`, and `mvnw` stay at the repo root\nunchanged.\n- Surefire\u0027s `java.library.path` now uses\n`${maven.multiModuleProjectDirectory}` so it resolves under the reactor\nregardless of which module Maven is invoked from.\n- `apache-rat-plugin` runs only at the root\n(`\u003cinherited\u003efalse\u003c/inherited\u003e`); the rat exclude list is unchanged.\n\n**Three runnable examples** under\n`examples/src/main/java/org/apache/datafusion/examples/`:\n\n- `SqlQueryExample` — `registerCsv` + a SQL `GROUP BY` aggregation.\n- `DataFrameExample` — `readCsv` → `filter` / `select` /\n`withColumnRenamed` / `distinct` → `writeParquet(singleFileOutput)` →\n`readParquet` round-trip.\n- `ProtoPlanExample` — build a `LogicalPlanNode` directly via the\ngenerated protobuf classes and execute it through\n`SessionContext.fromProto`.\n\nEach example creates its own throwaway data in a temp dir and cleans up,\nso no external fixtures (TPC-H, etc.) are required.\n\n**Docs:** `docs/source/contributor-guide/development.md` is updated with\nthe new repo layout and a \"Running an example\" section that documents\nthe `./mvnw install -DskipTests` + `exec:exec` flow.\n\n## Are these changes tested?\n\n- The full JVM test suite (`./mvnw test`) still passes against the\nrelocated `core/src/test/` sources — 61 tests run, 0 failures (12\nskipped, same skip pattern as `main` when TPC-H data is absent).\n- Each example was executed end-to-end via `./mvnw -pl\n:datafusion-java-examples exec:exec` and produces expected output:\n - `SqlQueryExample` prints `HIGH 3 215 / MEDIUM 1 60 / LOW 1 25`.\n- `DataFrameExample` prints a 3-row deduped table and `Round-tripped row\ncount: 3`.\n - `ProtoPlanExample` prints `42 7`.\n- `spotless:check` and the reactor build are clean across all three\nmodules.\n\n## Are there any user-facing changes?\n\n- The published library artifact\n(`org.apache.datafusion:datafusion-java`) is unchanged — same `groupId`,\n`artifactId`, `version`, and package contents.\n- The repo layout changes: source paths move from `src/main/java/...` to\n`core/src/main/java/...`. IDE projects pointing at the old location need\nto re-import.\n- New `datafusion-java-examples` artifact exists but is marked\n`maven.install.skip\u003dtrue` / `maven.deploy.skip\u003dtrue` and is not intended\nfor distribution.", "tree_diff": [ { "type": "add", "old_id": "0000000000000000000000000000000000000000", "old_mode": 0, "old_path": "/dev/null", "new_id": "27c4276ca1eb4bfc195504ccac069b63c1753667", "new_mode": 33188, "new_path": "core/pom.xml" }, { "type": "rename", "old_id": "f44182073e7adec087ede58c894c983e94186ce3", "old_mode": 33188, "old_path": "src/main/java/org/apache/datafusion/CsvReadOptions.java", "new_id": "f44182073e7adec087ede58c894c983e94186ce3", "new_mode": 33188, "new_path": "core/src/main/java/org/apache/datafusion/CsvReadOptions.java", "score": 100 }, { "type": "rename", "old_id": "dceb497f4dee6602e0f37326521ef7262ade4dcc", "old_mode": 33188, "old_path": "src/main/java/org/apache/datafusion/DataFrame.java", "new_id": 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