Constant DISCOVER_PRIMARY_KEY_QUERY

const DISCOVER_PRIMARY_KEY_QUERY: &str = r#"
    SELECT a.attname as column_name
    FROM pg_index i
    JOIN pg_attribute a ON a.attrelid = i.indrelid AND a.attnum = ANY(i.indkey)
    WHERE i.indrelid = ($1 || '.' || $2)::regclass
      AND i.indisprimary = true
    ORDER BY array_position(i.indkey, a.attnum)
"#;

SQL query to discover primary key columns directly from PostgreSQL system tables. This bypasses querying information_schema.table_constraints to avoid permission issues.