[techgopal]

Adds the DSB benchmark to the bench harness as the dsb suite (P2-T141), for the join-enumerator comparison. DSB is a TPC-DS derivative with correlated and skewed data and 52 query templates; 28 of them join 8 or more base tables (up to 28).

Licence

• The microsoft/dsb repository is MIT.
• Its generator (dsdgen/dsqgen) and query templates come from the TPC-DS tools and are covered by the TPC End User License Agreement v2.2 (code/TPC_DS_EULA.txt): use on systems under the user's control, redistribution only with the EULA, results labelled as not comparable to TPC results.
• So this PR contains no generator source, templates or query text. The harness checks out a pinned upstream commit under $KRISHIV_DATA/cache/dsb/, builds the tools there (git, gcc and make only) and writes the instantiated queries into the dataset directory. Results are DSB results, not TPC-DS results.
• The licences are recorded in each dataset's MANIFEST.json.

What it does

• krishiv-datasets dsb --sf N: generates the data, converts it to Parquet, instantiates the queries, runs them in DuckDB and stores the answers as the oracle. Output goes to $KRISHIV_DATA/dsb/sf<N>-dbgen-v1/ and is never overwritten.
• krishiv-datasets dsb-verify <dir> recomputes the checksums.
• krishiv-bench run --suite dsb --dataset dsb@v1 compares each engine's rows with the oracle.
• The upstream C code reads uninitialised locals; the tools are built with -ftrivial-auto-var-init=zero so the output does not depend on the optimisation level. Two independent SF1 generations gave identical raw-file, Parquet and query checksums.

Not in this PR: reproduce, abba and ab do not know the suite yet. At SF1 many oracle answers are empty or one row (16 and 26 of 52); larger scales check more.

Checks: ruff check, ruff format --check, ty check, pytest in bench/ pass (12 new tests; no generator run in CI).

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Walkthrough

The benchmark package adds DSB dataset generation, verification, and runner support. Generated datasets include Parquet tables, instantiated queries, checksums, a manifest, and optional DuckDB oracle results.

Changes: DSB benchmark suite

Layer / File(s)	Summary
Prepare DSB source, tables, and queries bench/src/krishiv_bench/dsb.py, bench/tests/test_dsb.py	Adds pinned-source setup and generator builds, schema parsing, Parquet conversion, seeded query generation, and relation counts. Tests cover parsing, conversion, query IDs, and relation counts.
Generate and verify DSB datasets bench/src/krishiv_bench/dsb.py, bench/src/krishiv_bench/datasets.py, bench/README.md, bench/tests/test_dsb.py	Generates dataset files and optional oracle results, records metadata and checksums, and verifies required files and hashes. Adds dsb and dsb-verify CLI commands and documents dataset generation, contents, licensing, and supported commands. Tests cover verification, oracle handling, and deterministic serialization.
Run DSB queries with oracle answers bench/src/krishiv_bench/cli.py, bench/src/krishiv_bench/runner.py, bench/src/krishiv_bench/dsb.py, bench/tests/test_dsb.py	Adds DSB as a run suite and loads its queries and oracle rows from a dataset directory. The runner checks matching oracle rows before using official answers. Tests cover query loading and the missing-dataset case.

Priority: Normal

Estimated code review effort: 4 (Complex) | ~45 minutes

Possibly related PRs

• KrishivAI/krishiv-engine#147: Adds the versioned dataset naming and directory-path contract used by the DSB dataset mapping.
• KrishivAI/krishiv-engine#166: Changes join-planning behavior measured by the DSB join benchmark.

Merge Risk: Moderate · up to f91e7

CI is blocked by the DSB test fixture. Fix that failure before merging, and address the build provenance and conversion-test gaps.

Security architecture risk: Low · up to f91e7

The change remains an explicitly invoked benchmark workflow and adds no demonstrated privilege escalation. It does, however, execute third-party tools and dataset-resident SQL, making trusted cache and dataset storage important. Storage permissions and remote engine authorization are not established by the available evidence.

Retained concerns
No architecture-level concerns identified.

Security review details

Security Blast Radius

• inferred — Compromised generator binaries would execute with the invoking process's authority, and substituted SQL would execute with the selected engine's authority, including an operator-configured Spark Connect service. The evidenced scope is therefore broader than generated dataset files, but deployment permissions and any cross-tenant or production exposure remain unestablished.

Trust Boundaries and Controls

• observed — Fresh DSB acquisition checks a fixed repository commit, command execution uses argument lists rather than shell interpolation, and conversion paths escape SQL string quotes. These controls constrain acquisition and argument injection, but do not make cached tools or dataset SQL safe to accept from an untrusted writer.
• inferred — DSB extends executable-input trust to dataset-resident SQL under KRISHIV_DATA, which defaults to a directory in the user's home. Unlike the existing ClickBench loader, which rechecks cached SQL against pinned hashes, DSB loads query files directly. This is a meaningful provenance distinction, but no lower-trust actor with write access was established.

Resilience and Maintainability Implications

• observed — Oracle errors are recorded per query without aborting publication. Successful answers alone enter the oracle file, and the runner labels absent answers not_checked rather than pass. Verification establishes file-checksum consistency, not complete oracle coverage.
• inferred — Publication contains ordinary partial-generation failures, but cache mutation has no locking and staging ownership is process-scoped rather than invocation-scoped. Concurrent cache builds or same-process generation calls are therefore not isolated. This limits reproducibility and recovery guarantees; no cross-identity security consequence was demonstrated.

Hardening Proposals

• proposed — Make the trusted-executable-input status of cache and dataset directories explicit. If shared or imported datasets are supported, establish ownership controls and independently trusted provenance for executed tools and SQL; colocated checksums alone do not authenticate their publisher.

Pre-merge checks: 4 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 35.14% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 37 functions across 5 files. (1 skipped: …	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
Title check		The title clearly identifies the main change: adding the DSB many-join dataset, queries, and DuckDB oracle to the benchmark harness.
Description check		The description explains the purpose, implementation, licensing constraints, usage, limitations, and tests. It includes the task identifier and test results. The repository checklist is not reproduced…
Linked Issues check		Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check		Check skipped because no linked issues were found for this pull request.

Full details: Description check

Explanation

The description explains the purpose, implementation, licensing constraints, usage, limitations, and tests. It includes the task identifier and test results. The repository checklist is not reproduced, but the description is otherwise sufficiently complete.

Full details: Docstring Coverage

Explanation

Docstring coverage is 35.14% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 37 functions across 5 files. (1 skipped: 1 unsupported.)

Resolution

Write docstrings for the functions missing them to satisfy the coverage threshold.

Finishing Touches: 💡 1

🛠️ Fix failing CI checks: 💡

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Actionable comments posted: 3

🔇 Additional comments: 5

bench/src/krishiv_bench/datasets.py: 1

302-340: LGTM!

bench/README.md: 1

184-212: LGTM!

Also applies to: 256-256

bench/src/krishiv_bench/cli.py: 1

83-83: LGTM!

bench/src/krishiv_bench/runner.py: 1

25-25: LGTM!

Also applies to: 102-121, 178-201, 223-223, 280-292

bench/src/krishiv_bench/dsb.py-110-112: 1

110-112: Minor · Functional Correctness · Quick win

⚠️ Unverified finding
Verification ran but could not confirm this finding. It is shown for review, not as a verified issue.

Check the compiler version before building. The generator needs GCC 12 or later.

The module docstring says -ftrivial-auto-var-init=zero needs GCC >= 12. Zeroing the uninitialised locals is what makes the data reproducible. The only check is shutil.which, so build_tools accepts any gcc on PATH.

An older GCC fails inside make with an unrecognised-option error and gives no hint about the version. The README (uv run krishiv-datasets dsb --sf 1 # needs git, gcc, make) does not state the minimum version either.

Fail early with a clear message when the compiler is too old. Add "gcc >= 12" to the README note.

Proposed check

     for tool in ("gcc", "make"):
         if shutil.which(tool) is None:
             sys.exit(f"`{tool}` not found: building the DSB generator needs gcc and make")
+    ver = subprocess.run(["gcc", "-dumpversion"], capture_output=True, text=True).stdout.strip()
+    if not ver or int(ver.split(".")[0]) < 12:
+        sys.exit(f"gcc {ver or '?'} found: -ftrivial-auto-var-init=zero (needed for reproducible data) needs gcc >= 12")

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• 🪄 Fix comments: Fix CodeRabbit comments on this PR

Prompt to fix review comments

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Inline comments:
Review comments at @bench/src/krishiv_bench/dsb.py:
- Around line 105-109: Update build_tools so cached binaries are reused only
when their recorded build configuration matches the current TOOL_CFLAGS and
compiler version; otherwise rebuild them. Write the configuration stamp only
after the build succeeds, so the manifest cannot associate stale binaries with
new flags.

Review comments at @bench/tests/test_dsb.py:
- Line 132: Update the Latin-1 fixture in the test using dat.write_bytes to use
a non-ASCII word that does not trigger the typos check, while retaining a
Latin-1 byte; update the corresponding t[0]["b"] assertion to match the new
decoded value.
- Around line 141-148: Update test_convert_table_roundtrip to assert both
complete converted rows, including all columns, NULLs, and expected INTEGER,
DECIMAL, DATE, and TIME values. Replace the digit-only row_hash_sum check with
an exact comparison against an independent DuckDB calculation using the
implemented hash(t) contract; preserve the existing file hash assertion.

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Files selected for processing: 6

• bench/README.md
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[codspeed]

Merging this PR will improve performance by 10.92%

2 warnings

⚠️ 9 benchmarks are dominated by system calls

System calls cannot be simulated consistently and are left out of the measure. The reported value understates the real cost. Switch to the Walltime instrument to measure them.

Learn more about system calls

See affected benchmarks

⚠️ Base and head ran on different runner types

Some benchmarks with significant performance changes were compared across different runner types, so the changes might not come from the code. Run base and head on the same runner type, or use CodSpeed Macro Runners for more stable results.

Learn more about Macro Runners

Open the report in CodSpeed to investigate

⚡ 2 improved benchmarks
✅ 119 untouched benchmarks
⏩ 4 skipped benchmarks¹

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
⚡	4096_batches_4_empty_operators	81.7 ms	73.6 ms	+11.06%
⚡	256_batches_4_empty_operators	5.4 ms	4.8 ms	+10.79%

Tip

Curious why performance improved? Comment @codspeedbot explain why performance improved on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing bench/join-order-dataset (f0deaf7) with main (23732b9)²}

Footnotes

1. 4 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

2. No successful run was found on main (37df819) during the generation of this report, so 23732b9 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩