Fatal error: Allowed memory size of 536870912 bytes exhausted (tried to allocate 147456 bytes) in /var/www/wordpress/wp-includes/wp-db.php on line 1999

Fatal error: Allowed memory size of 536870912 bytes exhausted (tried to allocate 147456 bytes) in /var/www/wordpress/wp-includes/wp-db.php on line 1999