/**
 * postgres-mcp — Schema Operations: Describe
 *
 * Types, pure parsing helpers, and the `queryDescribeTable` function
 * for detailed table inspection (columns, indexes, constraints, foreign keys).
 */
import type { QueryResult, TableInfo } from "../../../types/index.js";
/**
 * A function that executes SQL and returns rows.
 * Matches PostgresAdapter.executeQuery signature.
 */
export type QueryExecutor = (sql: string, params?: unknown[]) => Promise<QueryResult>;
/**
 * Cache helpers, matching the getCached/setCache interface on PostgresAdapter.
 */
export interface CacheHelpers {
    getCached(key: string): unknown;
    setCache(key: string, data: unknown): void;
}
/**
 * Parse columns from PostgreSQL array format.
 * Handles both native arrays and string representations like "{col1,col2}".
 */
export declare function parseColumnsArray(columns: unknown): string[];
/**
 * Extract expression columns from index definition when column names are NULL.
 * Expression indexes (like LOWER(name)) have attnum=0 which returns NULL from pg_attribute.
 * This parses the index definition to extract the actual expressions.
 */
export declare function extractIndexColumns(columns: string[], definition: string): string[];
/**
 * Extract the column expression part from an index definition, handling nested parentheses.
 * E.g., "CREATE INDEX idx ON tbl USING btree (lower(name))" → "lower(name)"
 */
export declare function extractIndexExpressionPart(definition: string): string | null;
/**
 * Parse index expressions from the column list, handling nested parentheses.
 * E.g., "LOWER(name), id, UPPER(TRIM(email))" → ["LOWER(name)", "id", "UPPER(TRIM(email))"]
 */
export declare function parseIndexExpressions(columnList: string): string[];
/**
 * Describe a single table with columns, indexes, constraints, and foreign keys.
 */
export declare function queryDescribeTable(executeQuery: QueryExecutor, cache: CacheHelpers, tableName: string, schemaName?: string): Promise<TableInfo>;
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