[SESSION_127] SearchAgent: Implement Query Optimizer (Phase 23)

Feature: Query Optimization and Planning

Component: SearchAgent (/agents/search_agent/)
Severity: 🔴 CRITICAL BLOCKER
Session: SESSION 127 (Definition of Done)
Current Status: Naive query execution, no optimization
Target Phase: Phase 23

Context

SearchAgent currently executes queries inefficiently with full table scans on complex filters. Large datasets experience O(n) performance degradation, blocking scalability.

Requirements

• Query plan analysis (explain plan)
• Index selection and utilization
• Filter reordering (selectivity-based)
• Query execution cost estimation
• Parallel execution where possible

Impact

Without this feature:

• Performance degrades with dataset size
• Complex queries timeout (>5s target)
• Cannot scale to production loads
• Users frustrated by slow searches

Effort Estimate

• Query planner: 6-8 hours
• Index selection: 3-4 hours
• Testing with large datasets: 2-3 hours
• Total: 10-12 hours

Technical Approach

• SQL EXPLAIN plan parsing
• Selectivity estimation per filter
• Dynamic filter reordering
• Join order optimization
• Parallel query execution

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Generated by SESSION 127 FASE 2.7