Module optimizer 

Query optimizer for efficient execution

This module provides query optimization through clause reordering and AST transformations to maximize index usage and minimize evaluation cost.

Optimization Strategies

1. Flattening: Collapse nested AND/OR operators

   • AND(AND(A, B), C) → AND(A, B, C)
   • OR(OR(A, B), C) → OR(A, B, C)

2. Clause Reordering: Order AND clauses for optimal execution

   • Indexed fields first (can use index lookups)
   • Within indexed fields, order by selectivity (most selective first)
   • Non-indexed fields last (require full scans)

3. Selectivity Estimation: Heuristic estimates for field selectivity

   • kind: 0.1 (10%) - most selective indexed field
   • name: 0.01 (1%) - very selective
   • path: 0.3 (30%)
   • lang: 0.4 (40%)
   • text: 0.5 (50%) - least selective, not indexed

Example

use sqry_core::query::optimizer::Optimizer;
use sqry_core::query::registry::FieldRegistry;

let registry = FieldRegistry::with_core_fields();
let optimizer = Optimizer::new(registry);

// Optimize: text:TODO AND kind:function
// Result:   kind:function AND text:TODO (indexed first)
let optimized = optimizer.optimize(ast);

Structs

Optimizer

Query optimizer that reorders clauses for efficient execution