Run a single read-only SQL statement (SELECT / WITH / EXPLAIN / SHOW) against the configured PostgreSQL database and return the rows.

Rejects anything that isn't exactly one plain read-only statement — multiple statements, transaction-control keywords (COMMIT, ROLLBACK, BEGIN, ...), and any write/DDL/admin keyword anywhere in the query are all refused before the query is sent to the database. Results are capped at PG_GUARD_ROW_LIMIT rows (default 1000).

Return the PostgreSQL query plan for a read-only SELECT/WITH statement, without running it. Useful for checking whether a query will be slow before running it for real.

List the tables and views visible to the connected role in the given schema (default: public).

Report any write privilege (INSERT/UPDATE/DELETE/TRUNCATE) the connected role actually holds on any table. An empty list is the expected, safe result — anything else means the privilege layer of defense is missing and the role should be locked down (see README.md), even though the protocol and session layers still hold on their own.

List the columns of a table: name, data type, nullability, and default, in column order.