#14 feat: add PERF016 rule detecting repeated scans of the same table

[RAprogramm]

Closes #14

New performance rule PERF016 (Info): flags statements that scan one table multiple times (self-joins, repeated subqueries over the same data) by counting word-bounded FROM/JOIN references. A CTE, window function, or conditional aggregation usually reads the table once.

• README, Cargo.toml description, docs updated to 34 rules; version bumped to 0.15.0
• 3 new tests: subquery re-scan, self-join, single-scan negative

Local checks: fmt, clippy -D warnings, tests, cargo qual (0 issues), mdbook build — all green.

[github-actions]

Rust Diff Analysis

Tip

PR size is within limits. Good job keeping changes focused!

Limits — configured thresholds for this repository

Each metric is compared against its configured maximum. If any limit is exceeded, the PR check fails.

Metric	Value	Limit	Status
Production Units	6	30	✅
Weighted Score	11	100	✅
Lines Added	62	200	✅

Understanding the metrics:

• Production Units: Functions, structs, enums, traits, and other semantic code units in production code
• Weighted Score: Complexity score based on unit types (public APIs weigh more than private)
• Lines Added: Raw count of new lines in production code

Summary — breakdown of changes by category

Production code counts toward limits. Test code is tracked but doesn't affect limits.

Metric	Production	Test
Functions	4	-
Structs/Enums	1	-
Other	1	-
Lines added	+62	+19
Lines removed	-0	-0
Total units	6	3

Production Changes — 6 units modified

Semantic units (functions, structs, etc.) that were added or modified in production code.

File	Unit	Type	Changes
src/rules.rs:182-243	RuleRunner::with_config	function	+1 -0
src/rules/performance.rs:741-746	RepeatedTableScan	struct	+6 -0
src/rules/performance.rs:748-766	table_scan_count	function	+19 -0
src/rules/performance.rs:768-803	Rule for RepeatedTableScan	impl	+3 -0
src/rules/performance.rs:769-776	Rule for RepeatedTableScan::info	function	+8 -0
src/rules/performance.rs:778-802	Rule for RepeatedTableScan::check	function	+25 -0

Test Changes — 3 units modified

Test code changes don't count toward PR size limits.

File	Unit	Type	Changes
tests/rules_tests.rs:184-190	test_repeated_table_scan_flagged	function	+7 -0
tests/rules_tests.rs:192-198	test_self_join_flagged	function	+7 -0
tests/rules_tests.rs:200-204	test_single_scan_not_flagged	function	+5 -0

Analysis Scope

Analyzed: 3 Rust files

Skipped files:

• 6 non-Rust files

Skipped file list:

• Cargo.lock (non-Rust)
• Cargo.toml (non-Rust)
• README.md (non-Rust)
• docs/src/introduction.md (non-Rust)
• docs/src/rules/index.md (non-Rust)
• docs/src/rules/performance.md (non-Rust)

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_{Rust Diff Analyzer}

[github-actions]

Cargo Quality Analysis

Tip

All quality checks passed. Code meets all standards!

Results — issues found by each analyzer

Each analyzer checks for specific code patterns. Zero issues means the check passed.

Analyzer	Issues	Status
path_import	0	✅
format_args	0	✅
empty_lines	0	✅
inline_comments	0	✅
mod_rs	0	✅
Total	0

Analyzers — what each check does

These analyzers enforce consistent code style and best practices.

Analyzer	Description	How to fix
path_import	Detects inline path imports like std::path::Path	Use use statements at the top
format_args	Detects format!("{}", x) patterns	Use format!("{x}") syntax
empty_lines	Detects empty lines inside function bodies	Remove extra blank lines
inline_comments	Detects // comment inside functions	Move to doc comments or remove
mod_rs	Detects mod.rs files (use modern module style)	Rename foo/mod.rs to foo.rs

Raw Output — detailed analysis log

Total issues: 0
Fixable: 0

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_{Cargo Quality}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ All tests successful. No failed tests found.

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