I couldn’t tell you, it shouldn’t happen in the first place. Would need code
that illustrates the problem.
On Mar 27, 2014, at 9:27 PM, Ni Wesley <nisp...@gmail.com> wrote:
> MySQLdb has the same problem.
> So, no concurrent, I just use engine(with default connection pool) execute.
> Then, how to work around the problem, for my query operation, if catch this
> exception, query again?
>
>
> 在 2014年3月27日星期四UTC+8下午11时42分19秒，Michael Bayer写道：
>
> On Mar 27, 2014, at 9:14 AM, Ni Wesley <nis...@gmail.com> wrote:
>
>> It's not happening everytime.
>>
>> And I am not using mysql-python, instead, I use pymysql.
>>
>> So, the root cause is connection in bad state?
>> How to fix or work around from sqlalchemy side?
>
> I don’t really know, I’d need to have a short script which replicates it in
> order to identify the pattern exactly.
>
> if its pymysql, try another DBAPI. though this may be some artifact of the
> MySQL protocol.
>
> as always, if you’re doing anything with threads, concurrent use of a MySQL
> connection will usually lead to problems like this. but there can be other
> reasons too.
>
>
>
>
>>
>> Wesley
>>
>> 在 2014年3月27日星期四UTC+8下午8时58分40秒，Michael Bayer写道：
>> when the DBAPI cursor has no .description object, it is determined to not be
>> a result-row returning object. The MySQLDB DBAPI has been observed to
>> occasionally have issues in this area, when a connection gets into a bad
>> state. There are likely patterns in how you’re calling it that lead it to
>> have this issue but you might try a different DBAPI like
>> mysql-connector-python just to see what’s different.
>>
>>
>>
>>
>> On Mar 27, 2014, at 7:41 AM, Ni Wesley <nis...@gmail.com> wrote:
>>
>>> Hi all,
>>> Today I get an error as title.
>>> I use sqlalchemy + mysql.
>>> Here is my code snippet:
>>> def dbquery(_table,whereclause):
>>>
>>> try:
>>>
>>> #_table=Table(tablename, metadata, autoload=True)
>>>
>>> #_table = tables[tablename]
>>>
>>> i=_table.select().where(whereclause)
>>>
>>> if direct_engine: #direct_engine is True
>>>
>>> res = engine.execute(i)
>>>
>>> return res
>>>
>>> else:
>>>
>>> session = scoped_session(sessionmaker(bind=engine))
>>>
>>> res = session.execute(i)
>>>
>>> return res
>>>
>>> session.close()
>>>
>>> except Exception,e:
>>>
>>> #dba_logger.log(40,'Exception when dbwriter:%s' % str(e))
>>>
>>> #dba_logger.log(20,'Exception detail:%s' % str(kwargs))
>>>
>>> exctrace('db','1','Error happened when querying
>>> db',dba_logger,'Exception when dbquery:%s' % str(e),'Exception detail:%s' %
>>> str(whereclause))
>>>
>>> #session.rollback()
>>>
>>> if not direct_engine:
>>>
>>> session.close()
>>>
>>> Here is snippet in another file involving dbquery:
>>>
>>> try:
>>>
>>> res =
>>> dbquery(tables['sessions_details'],whereclause=and_(tables['sessions_details'].c.app_key==self.app_key,tables['sessions_details'].c.device_token==self._devicetoken))
>>>
>>> except Exception,e:
>>>
>>> exctrace('db','1','Error happened when querying
>>> db',dba_logger,'Exception when query session_details:%s' %
>>> str(e),'Exception detail:appkey is %s,devicetoken is %s' %
>>> (self.app_key,self._devicetoken))
>>>
>>> self.read_message()
>>>
>>> return
>>>
>>> if res is None:
>>>
>>> logger.log(40,'When query connection,mysql has gone or something, just
>>> skip db and go-on')
>>>
>>> #here need to justify 0 or 1, later on
>>>
>>> self.status='0'
>>>
>>> self.read_message()
>>>
>>> return
>>>
>>> if res.first() is None:
>>>
>>> if json_obj['action'] == 'reg':
>>>
>>> So, the line in pink above raises the exception.
>>>
>>> Could anyone give some suggestion how this happened?
>>>
>>>
>>>
>>> Thanks.
>>>
>>> Wesley
>>>
>>>
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>>
>>
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