/**
 * Query Planner - Cost-Based Index Selection
 *
 * Analyzes queries and selects the optimal index to use.
 * Uses cardinality estimation and index statistics to minimize query cost.
 */
import type { IndexConfig } from './index-types.js';
export interface QueryPredicate {
    field: string;
    operator: 'eq' | 'gt' | 'gte' | 'lt' | 'lte' | 'in' | 'range' | 'contains' | 'startsWith';
    value?: any;
    values?: any[];
}
export interface IndexScoreboard {
    indexName: string;
    indexType: string;
    fields: string[];
    score: number;
    coverage: number;
    estimatedRows: number;
    cost: number;
}
export declare class QueryPlanner {
    /**
     * Analyze a predicate and select the best index.
     */
    static planQuery(predicates: QueryPredicate[], indexes: IndexConfig[]): IndexScoreboard | null;
    /**
     * Score how well an index covers the given predicates.
     */
    private static scoreIndex;
    /**
     * Explain the query plan (for debugging).
     */
    static explainPlan(predicates: QueryPredicate[], indexes: IndexConfig[], selectedIndex?: IndexScoreboard): string;
}
/**
 * Compound query builder for multi-field searches.
 */
export declare class CompoundQuery {
    private predicates;
    private fields;
    /**
     * Add a predicate for a field.
     */
    addPredicate(field: string, operator: QueryPredicate['operator'], value: any): this;
    /**
     * Get all predicates.
     */
    getPredicates(): QueryPredicate[];
    /**
     * Get fields involved in this query.
     */
    getFields(): string[];
    /**
     * Find best index for this compound query.
     */
    planWith(indexes: IndexConfig[]): IndexScoreboard | null;
}
/**
 * Index recommendation engine - suggests indexes to create.
 */
export declare class IndexRecommender {
    /**
     * Analyze query patterns and recommend indexes.
     */
    static recommendIndexes(queries: QueryPredicate[][]): IndexConfig[];
}
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