只读数据库上的PDO :: exec（）不返回

Question

I'm investigating the effect of running MySQL in read-only mode on my code.I'm running MySQL 5.5.49.0 combined with PHP 5.5.9.1 (on Ubuntu 14.04). I set the database to read-only using the following commands:

flush tables with read lock;
set global read_only = 1;

If I connect via CLI and attempt an insert I get:

ERROR 1223 (HY000): Can't execute the query because you have a conflicting read lock

If I connect with the same user via PDO:

$pdo = new PDO('mysql:dbname=database;host=host', 'username', 'password', [
    PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
]);
try {
    $result = $pdo->exec('insert ***');
    die(var_dump(__LINE__, $result));
} catch (Exception $e) {
    die(var_dump(__LINE__, $e->getMessage()));
}

The browser keeps loading infinitly. I have tried a simular construction with good old mysql_connect and mysql_query and in that case the read-only situation is ignored and 0 is returned. Also not a workable solution.

I would rather not check pre-emptive if the database is running in read-only mode, because this is usually not the case and thus I can save an extra query every request.

So my question: how do I get an Exception or warning in any other form from Mysql/PDO?

Answer 1

It turns out I was connecting to my local development database (with my Vagrant instance) using a user with SUPER privileges. Users with SUPER privileges are not affected by the read_only option.

When I switched to a normal user I did get an Exception.

Another option you can consider is to use super_read_only instead of normal read_only.