docs/test: document Spark JDBC READ_COMMITTED and TopN ANY NULL

[Lundomn]

What type of PR is this?

• API-change
• BUG
• Improvement
• Documentation
• Feature
• Test and CI
• Code Refactoring

Which issue(s) this PR fixes:

Fixes #29838
Related to #29968 (TopN ANY NULL regression coverage)

What this PR does / why we need it:

Spark 3.5.3's JDBC writer defaults to READ_UNCOMMITTED, which MatrixOne rejects before inserting rows. This documents the supported isolationLevel=READ_COMMITTED option for Spark JDBC writes, links the guide from both root READMEs, and adds a runnable compatibility probe. MatrixOne's isolation behavior is unchanged.

The probe checks the default writer's MatrixOne 20105 error and empty target, then writes from two nonempty Spark writer partitions with READ_COMMITTED and verifies readback through a fresh Spark JDBC read and a separate JDBC connection.

The TopN test is a separate upstream CI test-contract addition. It keeps unsupported tuple/interval types as negative cases, retains the ANY Prepare-success cases already on main in #29862, and exercises nonliteral ANY NULL through actual partition TopN execution. TestPartitionTopNNonLiteralAnyNullOrder checks output NULLs, payload/group cardinality, flat and constant NULL batches, Reset reuse, and pool cleanup. This consolidates the TopN coverage from #29975; no production code changes.

Validation

• Complete pkg/sql/colexec/partition package passed through the repository CGo wrapper on combined head ca733a4b001b364ab467521b182fdb199d2c40ad (2.197s).
• gofmt and git diff --check passed.
• Spark-side build and probe evidence is from the unchanged Spark files and production source head 73e54458d1a4cd209f9d8eda7795242935880551: build passed; Spark 3.5.3 / Connector/J 8.0.33 / JDK 17 verified READ_UNCOMMITTED rejection (20105), empty target, successful READ_COMMITTED two-partition write, fresh Spark JDBC read and separate SQL readback, and cleanup. The probe was not rerun after the TopN test-only addition.
• Focused BVT test/distributed/cases/set/set_transaction.sql passed 30/30 on base 035a5b61ba84ffc7dd2193135a7b170af04a4bff. An attempt on source head 73e54458d1a4cd209f9d8eda7795242935880551 failed during mo-tester's pre-test database cleanup after connection retries, before any case ran; no BVT result is claimed for combined head ca733a4b001b364ab467521b182fdb199d2c40ad.
• At the post-push snapshot, CI preflight, PR size, coverage eligibility, and Mergify Summary passed. UT Test on Ubuntu/x86, SCA on Linux/arm64, shared build, and UT Coverage on Ubuntu/x86 were pending; other listed jobs were skipped. Full remote CI has not passed.

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[XuPeng-SH]

mo-bot review · mo-bot-local · done

Commit: ca733a4b001b364ab467521b182fdb199d2c40ad

Assessment: approve

Reviewed the complete six-file delta and relevant isolation, comparison, and operator lifecycle owners. The Spark guidance and compatibility probe match existing behavior; TopN tests preserve rejection coverage and exercise ANY NULL execution, Reset reuse, and cleanup. No actionable defects remain. Production code is unchanged.

Model: gpt-6-astra / xhigh

Session: 01a12d8f-8e48-7622-ad17-b605f08450ce · slot 1 · generation 0

Validation:

• Verified frozen head/base, clean checkout, and patch identity. Python syntax, Go formatting, local link targets, and git diff --check passed.

• Reused the reported complete partition-package pass on the exact head and successful frozen CI results for build, UT, SCA, coverage, and applicable BVT jobs.

• Reused the reported Spark 3.5.3/Connector/J 8.0.33/JDK 17 probe on 73e5445: default rejection, empty target, two-partition READ_COMMITTED write, independent readback, and cleanup. Only TopN tests differ from that revision.

• Reconciled both attempts and all supplied comments; no substantive reviewer concerns were present. Detailed evidence is recorded in attempt-2/review-evidence.json.

Limitations:

• No local native or Spark rerun; runtime results are attributed to supplied author and CI evidence.

• The focused transaction BVT attempt failed before executing cases and is not counted as a PR-head pass.

• Standalone linked-issue bodies were not supplied. Compatibility evidence covers the pinned environment, not a version matrix or distributed retry/atomicity guarantees.

[XuPeng-SH]

mo-bot review · mo-bot-local · review

Commit: ca733a4b001b364ab467521b182fdb199d2c40ad

Assessment: approve

Reviewed the complete six-file delta and relevant isolation, comparison, and operator lifecycle owners. The Spark guidance and compatibility probe match existing behavior; TopN tests preserve rejection coverage and exercise ANY NULL execution, Reset reuse, and cleanup. No actionable defects remain. Production code is unchanged.

Model: gpt-6-astra / xhigh

Session: 01a12d8f-8e48-7622-ad17-b605f08450ce · slot 1 · generation 0

Validation:

• Verified frozen head/base, clean checkout, and patch identity. Python syntax, Go formatting, local link targets, and git diff --check passed.

• Reused the reported complete partition-package pass on the exact head and successful frozen CI results for build, UT, SCA, coverage, and applicable BVT jobs.

• Reused the reported Spark 3.5.3/Connector/J 8.0.33/JDK 17 probe on 73e5445: default rejection, empty target, two-partition READ_COMMITTED write, independent readback, and cleanup. Only TopN tests differ from that revision.

• Reconciled both attempts and all supplied comments; no substantive reviewer concerns were present. Detailed evidence is recorded in attempt-2/review-evidence.json.

Limitations:

• No local native or Spark rerun; runtime results are attributed to supplied author and CI evidence.

• The focused transaction BVT attempt failed before executing cases and is not counted as a PR-head pass.

• Standalone linked-issue bodies were not supplied. Compatibility evidence covers the pinned environment, not a version matrix or distributed retry/atomicity guarantees.

[mergify]

Merge Queue Status

• ✅ Entered queue — 2026-10-12 10:16 UTC · Rule: main · triggered by rule Automatic queue on approval for main
• 🟠 Checks running · in-place
• 🚫 Left the queue — 2026-10-12 10:17 UTC · at 8cf88dbe5d24d94217d381aec17995c7e179a3b6

This pull request spent 1 minute 9 seconds in the queue, with no time running CI.

Reason

Pull request #29953 has been dequeued

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  • docs/test: document Spark JDBC READ_COMMITTED and TopN ANY NULL #29953
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