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ln-812-query-optimizer
Type: L3 Worker Category: 8XX Optimization Parent: ln-810-performance-optimization-coordinator
Fixes query efficiency issues found by ln-651-query-efficiency-auditor. Each fix verified via tests with keep/discard pattern. Metric: query count reduction (not runtime benchmark).
Overview
| Aspect | Details |
|---|---|
| Input | Audit findings from docs/project/persistence_audit.md (ln-651 section) OR target file |
| Output | Optimized queries, verification report |
| Companion | ln-651-query-efficiency-auditor (finds issues) → ln-812 (fixes them) |
Workflow
Phases: Pre-flight → Load Findings → Prioritize → Fix Loop → Report
Phase 0: Pre-flight Checks
| Check | Required | Action if Missing |
|---|---|---|
| Audit findings OR target file | Yes | Block optimization |
| Test infrastructure | Yes | Block (need tests for verification) |
| Git clean state | Yes | Block (need clean baseline for revert) |
MANDATORY READ: Load shared/references/ci_tool_detection.md — use Test Frameworks section for test detection.
Worktree & Branch Isolation
MANDATORY READ: Load shared/references/git_worktree_fallback.md — use ln-812 row.
Phase 1: Load Findings
From Audit Report
Read docs/project/persistence_audit.md, extract ln-651 findings:
| Finding Type | Optimization |
|---|---|
| N+1 query | Batch loading / eager loading / .Include() / prefetch_related |
| Redundant fetch | Pass object instead of ID, cache result |
| Over-fetching | Select specific fields / projection / .Select() |
| Missing index hint | Add index annotation / migration |
| Unbounded query | Add .Take() / LIMIT / pagination |
From Target File
If no audit report: scan target file for query patterns matching the table above.
Phase 2: Prioritize Fixes
| Priority | Criteria |
|---|---|
| 1 (highest) | N+1 in hot path (called per request) |
| 2 | Redundant fetches (same entity loaded multiple times) |
| 3 | Over-fetching (SELECT * where few columns needed) |
| 4 | Missing pagination on user-facing endpoints |
Phase 3: Fix Loop (Keep/Discard)
Per-Fix Cycle
FOR each finding (F1..FN):
1. APPLY: Edit query code (surgical change)
2. VERIFY: Run tests
IF tests FAIL → DISCARD (revert) → next finding
3. VERIFY: Tests PASS → KEEP
4. LOG: Record fix for report
Keep/Discard Decision
| Condition | Decision |
|---|---|
| No tests cover affected file/function | SKIP finding — log as "uncovered, skipped" |
| Tests pass | KEEP |
| Tests fail | DISCARD + log failure reason |
| Fix introduces new N+1 | DISCARD |
Note: No benchmark needed — query optimization metric is correctness (tests pass) + structural improvement (fewer queries). The audit already identified the inefficiency.
Phase 4: Report Results
Report Schema
| Field | Description |
|---|---|
| source | Audit report path or target file |
| findings_total | Total findings from audit |
| fixes_applied | Successfully kept fixes |
| fixes_discarded | Failed fixes with reasons |
| fix_details[] | Per-fix: finding type, file, before/after description |
Configuration
Options:
# Source
audit_report: "docs/project/persistence_audit.md"
target_file: "" # Alternative to audit report
# Verification
run_tests: true
# Scope
fix_types: # Filter which types to fix
- n_plus_one
- redundant_fetch
- over_fetching
- unbounded_query
Error Handling
| Error | Cause | Solution |
|---|---|---|
| No audit findings | ln-651 not run or no issues | Report "no findings to optimize" |
| ORM-specific syntax | Unknown ORM | Query Context7/Ref for ORM docs |
| Migration needed | Index addition requires migration | Log as manual step, skip |
References
../ln-651-query-efficiency-auditor/SKILL.md(companion: finds issues)shared/references/ci_tool_detection.md(test detection)
Definition of Done
- Findings loaded from audit report or target file scan
- Fixes prioritized (N+1 first, then redundant, over-fetch, unbounded)
- Each fix applied with keep/discard: tests pass → keep, tests fail → discard
- No new query inefficiencies introduced by fixes
- Report returned with findings total, fixes applied, fixes discarded
Version: 1.0.0 Last Updated: 2026-03-08