```
Caught exception while loading metadata: Code: 501, e.displayText() = DB::Exception: Cannot create MySQL database, because Code: 393, e.displayText() 
= DB::Exception: There is no query, Stack trace (when copying this message, always include the lines below):

0. /home/milovidov/ClickHouse/build_gcc9/../contrib/poco/Foundation/src/Exception.cpp:27: Poco::Exception::Exception(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, 
int) @ 0x1074687c in /usr/bin/clickhouse
1. /home/milovidov/ClickHouse/build_gcc9/../src/Common/Exception.cpp:37: DB::Exception::Exception(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, int) @ 0x7867c29 in
 /usr/bin/clickhouse
2. /home/milovidov/ClickHouse/build_gcc9/../contrib/libcxx/include/string:2134: DB::Context::getQueryContext() const (.cold) @ 0xd202416 in /usr/bin/clickhouse
3. /home/milovidov/ClickHouse/build_gcc9/../src/Interpreters/Context.h:457: DB::DatabaseConnectionMySQL::DatabaseConnectionMySQL(DB::Context const&, std::__1::basic_string<char, std::__1::char_traits<char>, std:
:__1::allocator<char> > const&, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&, DB::ASTStorage const*, std::__1::basic_string<char, std::__1::char_traits<char>, std:
:__1::allocator<char> > const&, mysqlxx::Pool&&) @ 0xd408d7c in /usr/bin/clickhouse
```

```
ATTACH DATABASE conv_main
ENGINE = MySQL('hostname:3306', 'db', 'metrika', 'password')
```
{
    Poco::File(getMetadataPath()).remove(true);
}
void DatabaseConnectionMySQL::cleanOutdatedTables()
{
    setThreadName("MySQLDBCleaner");
    std::unique_lock lock{mutex};
    while (!quit.load(std::memory_order_relaxed))
    {
        for (auto iterator = outdated_tables.begin(); iterator != outdated_tables.end();)
        {
            if (!iterator->unique())
                ++iterator;
            else
            {
                const auto table_lock = (*iterator)->lockExclusively(RWLockImpl::NO_QUERY, lock_acquire_timeout);
                (*iterator)->shutdown();
                (*iterator)->is_dropped = true;
                iterator = outdated_tables.erase(iterator);
            }
        }
        cond.wait_for(lock, cleaner_sleep_time);
    }
}
void DatabaseConnectionMySQL::attachTable(const String & table_name, const StoragePtr & storage, const String &)