Rename vortex_bench_dir to bench_results_dir

[joseph-isaacs]

Rationale for this change

Inside the vortex-bench crate, the vortex_bench_ prefix on vortex_bench_dir() is redundant and stutters at call sites (vortex_bench::output::vortex_bench_dir()), and the old name did not say what the directory is for. The new name matches the function's own doc comment: the base directory for benchmark results.

What changes are included in this PR?

• Rename vortex_bench_dir() to bench_results_dir() in vortex-bench/src/output.rs and update its single internal call site in default_output_path().
• No behavior change: the on-disk location is still target/vortex-bench/<benchmark-id>/results.json.

Verified with cargo check -p vortex-bench, cargo clippy -p vortex-bench --all-targets, cargo test -p vortex-bench --lib output, and cargo +nightly fmt --all.

What APIs are changed? Are there any user-facing changes?

The function is pub in the output module of vortex-bench, but the crate is publish = false benchmark tooling and no other crate in the workspace references the function, so there is no user-facing impact.

🤖 Generated with Claude Code

https://claude.ai/code/session_01XmiEZHiQf7joDWHFF9YSXo

---

Generated by Claude Code

[github-actions]

Polar Signals Profiling Results

Latest Run

Status	Commit	Job	Attempt	Link
🟢 Done	1675eff		1	Explore Profiling Data

---

Powered by Polar Signals Cloud

[codspeed-hq]

Merging this PR will degrade performance by 10.05%

❌ 1 regressed benchmark
✅ 1669 untouched benchmarks
⏩ 53 skipped benchmarks¹

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	true_count_vortex_buffer[128]	522.2 ns	580.6 ns	-10.05%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

---

_{Comparing claude/benchmarks-function-naming-g5qu2t (1675eff) with develop (60c1227)}

Footnotes

1. 53 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. ↩

[github-actions]

Benchmarks: Vortex queries

Verdict: No clear signal (low confidence)
Attributed Vortex impact: +2.8%
Engines: DataFusion No clear signal (+9.7%, medium confidence) · DuckDB No clear signal (-3.7%, low confidence)
Vortex (geomean): 0.981x ➖
Parquet (geomean): 0.967x ➖
Shifts: Parquet (control) -3.3% · Median polish -1.8%

How to read Verdict and Engines

• Verdict: Overall PR-level signal after subtracting baseline drift estimated from Parquet control rows. It can be Likely improvement, Likely regression, or No clear signal.
• Engines: Per-engine attribution. DataFusion is compared against DataFusion/Parquet controls; DuckDB is compared against DuckDB/Parquet controls. This answers whether each engine improved or regressed independently.
• Confidence: Based on directional consistency, share of rows above the noise floor, and control-run noise.

---

datafusion / vortex-file-compressed (1.026x ➖, 0↑ 0↓)

name	PR 1675eff (ns)	base 60c1227 (ns)	ratio (PR/base)
vortex_q00/datafusion:vortex-file-compressed	9560193	9622169	0.99
vortex_q01/datafusion:vortex-file-compressed	6486843	6124254	1.06

datafusion / parquet (0.935x ➖, 0↑ 0↓)

name	PR 1675eff (ns)	base 60c1227 (ns)	ratio (PR/base)
vortex_q00/datafusion:parquet	19819527	21179208	0.94
vortex_q01/datafusion:parquet	4534636	4850601	0.93

duckdb / vortex-file-compressed (0.964x ➖, 0↑ 0↓)

name	PR 1675eff (ns)	base 60c1227 (ns)	ratio (PR/base)
vortex_q00/duckdb:vortex-file-compressed	10006057	10093295	0.99
vortex_q01/duckdb:vortex-file-compressed	5823891	6216890	0.94

duckdb / parquet (1.000x ➖, 0↑ 0↓)

name	PR 1675eff (ns)	base 60c1227 (ns)	ratio (PR/base)
vortex_q00/duckdb:parquet	23462333	23382995	1.00
vortex_q01/duckdb:parquet	9359335	9386126	1.00

---

No file size changes detected.