/**
 * AST-based SQL transformer for DuckDB compatibility.
 *
 * Transforms:
 * - Array bounds: array_lower(..., 1), array_upper(..., 1) -> DuckDB expressions
 * - JOIN column qualification: "col" = "col" -> "left"."col" = "right"."col"
 * - generate_series aliases and per arm WITH clauses in set operations
 *
 * Postgres array operators (@>, <@, &&) are native in DuckDB and pass through.
 *
 * Re-printing the AST is lossy (node-sql-parser applies backslash escapes to
 * string literals and misreads IS DISTINCT FROM $1), so the rewritten SQL is
 * only used when its literals, parameters and quoted identifiers match the
 * original query.
 *
 * Performance optimizations:
 * - LRU cache for transformed queries (avoids re-parsing identical queries)
 * - Smart heuristics to skip JOIN qualification when not needed
 * - Early exit when no transformation is required
 */
export type TransformResult = {
    sql: string;
    transformed: boolean;
};
export declare function transformSQL(query: string, options?: {
    qualifyJoinColumns?: boolean;
}): TransformResult;
/**
 * Clear the transformation cache. Useful for testing or memory management.
 */
export declare function clearTransformCache(): void;
/**
 * Get current cache statistics for monitoring.
 */
export declare function getTransformCacheStats(options?: {
    qualifyJoinColumns?: boolean;
}): {
    size: number;
    maxSize: number;
};
export { transformArrayBounds } from './visitors/array-bounds.ts';
export { qualifyJoinColumns } from './visitors/column-qualifier.ts';
export { rewriteGenerateSeriesAliases } from './visitors/generate-series-alias.ts';
export { hoistUnionWith } from './visitors/union-with-hoister.ts';