Prepared statement does not work for Symbol operators

What are you doing?

class User extends Model {}
User.init({
  id: { type: DataTypes.INTEGER, primaryKey: true, autoIncrement: true },
  email: { type: DataTypes.STRING },
  failed_logins: { type: DataTypes.INTEGER }
}, {
  sequelize,
  tableName: 'users'
});

What do you expect to happen?

await User.update({
  failed_logins: 0
}, {
  where: {
    id: 1,
    failed_logins: { [Op.eq]: 4 }
  }
});

Mysql general_log shows

# Actual
Prepare | UPDATE `users` SET `failed_logins`=? WHERE `id` = ? AND `failed_logins` = 4

But it is expected that failed_logins = ?

# Expected
Prepare | UPDATE `users` SET `failed_logins`=? WHERE `id` = ? AND `failed_logins` = ?

Environment

Dialect:

• mysql
• postgres
• sqlite
• mssql
• any Dialect mysql2 version: 1.6.5 Database version: 8.0.14 Sequelize version: 5.8.6 Node Version: v10.15.0 OS: Win10

[ephys]

That issue about prepared statements not being cleared is being tracked here: https://github.com/sequelize/sequelize/issues/10832, I’ll post a status update over there

[katreniak]

The substituted parameter values inside prepared statements cause prepared statements to leak inside db. To release them, the db connection has to be closed.

The db connections are typically closed on connection options.pool.idle timeout. But when the workload is able to keep all options.pool.max connections busy for long enough time, eventually the (in case of mysql) sysvar_max_prepared_stmt_count limit is reached and all subsequent db requests are denied with Can't create more than max_prepared_stmt_count statements.

Is there a way to prevent this problem?