[labianchin]

Motivation

Fixes #143: export JDBC tables directly to Parquet, not only Avro.

Change

Adds a dbeam-parquet module that reuses dbeam-core for connections, query building, partitioning, parallel queries and metering.

This branch is stacked on #1046 (Beam 2.77.0 and JDBC driver bumps). Until #1046 merges, its two commits also show here. Review from 66c0f29 onwards.

Review guide

One commit per concern, best read in order:

1. Drop Java 11 support, raise floor to JDK 17: CI matrix and compiler release.
2. Parameterize shade plugin main class with dbeam.mainClass: each module sets its own shaded-jar main class. The dbeam-core jar is unchanged.
3. Extract format-agnostic JdbcMetering and BenchJdbcJob: shared metering and benchmark code moves out of the Avro classes. JdbcAvroMetering becomes a subclass and keeps its metric namespace, so Dataflow counters keep their names. PsqlReplicationCheck.validateOptions becomes public. No behavior change for Avro.
4. Add dbeam-parquet module: JdbcParquetJob, PsqlParquetJob, BenchJdbcParquetJob, schema conversion, write support, and tests. This is the bulk of the PR.
5. Run Parquet exports in e2e tests and CI: Parquet e2e suite validated with parquet-tools, and Codecov for the new module.
   • PostgreSQL goes from 16 to 18. The data volume now mounts at /var/lib/postgresql, because 18+ images refuse the old /var/lib/postgresql/data mount.
   • parquet-cli runs with hadoop-mapreduce-client-core and the dbeam-parquet shaded jar on its classpath, since its runtime jar doesn't bundle Hadoop.
   • Codecov thresholds are relaxed: project may drop up to 3 points, patch up to 5 points below base.
6. Document dbeam-parquet module: README, docs/parquet-type-conversion.md, CHANGELOG.

Parquet behavior:

• The Parquet schema comes from JDBC metadata. --parquetSchemaFilePath overrides it.
• SQL ARRAY columns become Parquet LIST columns with typed elements, and --arrayMode is honored. bytea[] elements are written as BINARY.
• UUID is written as FIXED_LEN_BYTE_ARRAY(16). DATE and TIMESTAMP are written as TIMESTAMP(MILLIS).
• The file footer stores the Avro schema under the parquet.avro.schema key. If dbeam-core can't build that Avro schema (for example, a typed_first_row ARRAY column that is NULL on the first row), the job logs a warning and leaves the key out. The export doesn't fail.
• New options: --parquetCodec, --rowGroupSize (default 128MB) and --pageSize. Without --parquetCodec, --avroCodec maps to the closest Parquet codec.

Known limitation: --useTimestampMicros (#1042) does not apply to Parquet yet. Parquet timestamps are always MILLIS, so the footer Avro schema is generated with micros disabled to match. Supporting micros can be a follow-up.

Also a follow-up: --parquetSchemaFilePath isn't checked against the JDBC metadata. The writers still take column types from JDBC, so a schema file should only rename fields or change annotations.

Expected impact

• Avro exports and the dbeam-core shaded jar behave as before.
• Users get a new dbeam-parquet artifact, which is also listed in dbeam-bom.
• Users on Java 11 must move to Java 17 or later.

Risk/rollback

• Most of the code is in the new, separate module.
• The shared-code risk is in commit 3 (metering and benchmark extraction), which existing Avro tests cover.
• Adding hadoop-common brings in more transitive dependencies. woodstox and stax2 are pinned, and a few enforcer excludes were added, to satisfy requireUpperBoundDeps.
• To roll back, revert the PR.

Validation

• mvn verify passes on the full build, including the enforcer and dbeam-core and dbeam-parquet tests.
• mvn verify -pl dbeam-core -am passes on commit 3 alone.
• CI is green on JDK 17, 21 and 25. The JDK 21 job runs e2e (e2e/e2e.sh), which covers the Avro and Parquet suites and checks the parquet.avro.schema footer.
• Codecov passes with the relaxed thresholds: project 89.09% against master's 91.87%, and patch 86.87%. Most of the remaining gap is in branches of the new module that are only partly covered.

Checklist for PR author(s)

• Changes are covered by unit tests (no major decrease in code coverage %) and/or integration tests.
• Ensure code formatting (use mvn com.coveo:fmt-maven-plugin:format org.codehaus.mojo:license-maven-plugin:update-file-header)
• Document any relevant additions/changes in the appropriate spot in javadocs/docs/README.

[codecov]

Codecov Report

❌ Patch coverage is 87.15847% with 94 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.33%. Comparing base (b05b278) to head (dff8833).

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #1040      +/-   ##
============================================
- Coverage     91.87%   89.33%   -2.55%     
- Complexity      288      436     +148     
============================================
  Files            27       39      +12     
  Lines          1034     1669     +635     
  Branches         90      161      +71     
============================================
+ Hits            950     1491     +541     
- Misses           55      106      +51     
- Partials         29       72      +43     

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