[R-sig-DB] RMySQL doesn't auto-reconnect

[Paul Gilbert]

Jack Tanner wrote:
> Unfortunately, the server in question is on a web host, so I almost 
> certainly have no control of time-out parameters, even just to play with 
> to test the hypothesis. The loss of connection usually happens within 
> seconds, not even tens of seconds. Connecting from a different client 
> machine still results in "server has gone away."

My guess is that this is not a time-out problem.  If you can arrage to 
temporarly connect without the firewall in the middle then at least you 
could determine if the problem is the server or the firewall.

> 
> I agree that auto-reconnect is a kludge, but I don't really know how to 
> diagnose the failure of the connection. Ideas welcome. :)
> 
> Could you clarify why auto-reconnect is dangerous security-wise?

I was assuming a situation that may not apply: if you use a 
userid/password to connect then you should probably worry about how easy 
it is to reconnect to a session that has been disconnected because it 
has been idle for awhile. (But I was thinking hours not seconds.)

Paul
> 
> Paul Gilbert wrote:
> 
>> Jack
>>
>> It is possible this is a firewall, but I think there is also a 
>> connection timeout parameter on the server, which can be adjusted. I'm 
>> not sure what the default is, but I don't usually have trouble unless 
>> I leave a connection sitting idle overnight. Probably the firewall has 
>> some sort of connection timeout too. I think both these timeouts 
>> should depend on idle time, so are not consistent with the problem you 
>> report.
>>
>> Auto-reconnect would fix your problem, but I don't think you should be 
>> getting dropped in the first place, unless you are really leaving the 
>> connection idle for a long time.  If you are doing that, I would not 
>> recommend auto-reconnect  (for security reasons).
>>
>> Paul
>>
>> Jeffrey Horner wrote:
>>
>>> Jack Tanner wrote:
>>>
>>>> After I do library(RMySQL), dbConnect(), and run a few queries, I 
>>>> sometimes get this:
>>>>
>>>> Error in mysqlExecStatement(conn, statement, ...) :
>>>>  RS-DBI driver: (could not run statement: MySQL server has gone away)
>>>>
>>>> If I issue a dbConnect() again, I can run queries again ... for a 
>>>> little while, and then I get another "server has gone away".
>>>>
>>>> The MySQL server is on a separate machine from the client. It's 
>>>> entirely possible that there's one or more firewalls in between, 
>>>> which could be causing the problem. The
>>>>
>>>> I understand that MySQL has auto-reconnect functionality:
>>>>
>>>> http://blog.taragana.com/index.php/archive/how-to-enable-disable-auto-reconnect-in-mysql/ 
>>>>
>>>>
>>>> Does RMySQL allow me to turn on auto-reconnect? If so, how?
>>>
>>>
>>>
>>> Unfortunately it doesn't right now, but that would be a great 
>>> addition. I've often had to test for the connection going away for 
>>> unknown reasons as well.
>>>
>>> I'll pencil it in for the next release as it's easy to add.
>>>
>>> Jeff
>>>
>>>>
>>>> > version
>>>>               _                          platform       
>>>> i386-redhat-linux-gnu      arch           i386                       
>>>> os             linux-gnu                  system         i386, 
>>>> linux-gnu            status                                    
>>>> major          2                          minor          
>>>> 9.1                        year           2009                       
>>>> month          06                         day            
>>>> 26                         svn rev        48839                      
>>>> language       R                          version.string R version 
>>>> 2.9.1 (2009-06-26)
>>>> > mysqlClientLibraryVersions()
>>>> 5.0.45 5.0.45
>>>> 50045  50045
> 
> 
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