[Qt-interest] [SOLVED] QSQLITE and Network Shares

[Israel Brewster]

So it turns out the problem was with Qt after all, specifically with  
the SQLite library provided with the Qt source code.  Once I  
recompiled Qt using the -system-sqlite flag, the problem went away,  
and SQLIte now works fine with the database located on a network  
directory. I'll go ahead and submit a bug report on the included  
SQLite libraries now.

On Nov 16, 2009, at 1:59 PM, Bill King wrote:

> On 11/17/2009 05:07 AM, ext Israel Brewster wrote:
>>
>>
>> On Nov 15, 2009, at 2:13 PM, Bill King wrote:
>>
>>>>
>>>>>
>>>>>
>>> The problem is an sqlite problem. What you are seeing is that  
>>> another query has a lock open on the table, and your query is  
>>> trying to elevate it's lock status.
>>
>> First off yes- PostgreSQL is a good option, and one I have  
>> implemented. I do agree that it is the way to go, however I also  
>> think that leaving something non-functional just because there is a  
>> better option is not acceptable. Of course, if this is a sqlite  
>> problem, then it's not your issue.
>>
>> That said, there are two serious flaws with your argument that this  
>> is an sqlite problem. First, there ISN'T another query that has a  
>> lock on the table. Look at the unit test I sent (with my first  
>> follow-up) - it creates a brand new database, opens it, and  
>> IMMEDIATELY tries to run a CREATE TABLE, getting this error (if on  
>> a network drive). The database hasn't even existed for more than a  
>> fraction of second. How and what could POSSIBLY have another query  
>> with a lock on the table, unless Qt itself put it there in the open  
>> command? Besides, the query I am running is a CREATE TABLE, so the  
>> table in question doesn't even exist when I run the query. How on  
>> earth could there be a lock on a table that doesn't exist?  
>> Actually, I get this error no matter the query I run, but using a  
>> CREATE TABLE query on a brand-new database precludes the  
>> possibility of a lock existing.
>>
>> Secondly, if I take Qt out of the equation, IT WORKS. Put Qt back  
>> into the equation, it doesn't work. Given that the only difference  
>> between the two tests was Qt (the test being create and open a  
>> brand-new database on a network share, and then run a CREATE TABLE  
>> query), how could this NOT be a Qt problem? I do apologize if I am  
>> being stubborn here, but saying it is a sqlite problem just doesn't  
>> fit the facts as I have presented them.
>>
>>>
>>> Seriously, I would consider a proper client/server database system  
>>> rather than trying to get what is essentially a single user system  
>>> to act in a networked fashion.
>>> There are lots of free/zero config databases out there. try  
>>> firebirdsql for instance, or postgresql, both have very permissive  
>>> licences, and cost you nothing.
>>
>> Agreed. That said, given that according to the official sqlite  
>> people this should work (and, in fact, does in testing once Qt is  
>> removed from the equation) doesn't it behoove you to make it work  
>> in Qt as well?
>>> -- 
>>> Bill King, Software Engineer
>>> Qt Development Frameworks, Nokia Pty Ltd
>>> Brisbane Office
>>>
>>> _______________________________________________
>>> Qt-interest mailing list
>>> Qt-interest at trolltech.com
>>> http://lists.trolltech.com/mailman/listinfo/qt-interest
>>
>> -----------------------------------------------
>> Israel Brewster
>> Computer Support Technician II
>> Frontier Flying Service Inc.
>> 5245 Airport Industrial Rd
>> Fairbanks, AK 99709
>> (907) 450-7250 x293
>> -----------------------------------------------
>>
> It does, and it will be tested in time. I'm still not convinced that  
> it's actually a qt issue, as we're not using sqlite in any funky  
> fashion (ie, we're using stock standard behaviour). However, If you  
> can add a bug report over at http://bugreports.qt.nokia.com/secure/Dashboard.jspa 
>  I'll schedule it and put it onto the list :) Including the test app/ 
> ways to reproduce is definitely most helpful. This way you can put a  
> track on it too, and it'll notify you when it's been handled.
>
> -- 
> Bill King, Software Engineer
> Qt Development Frameworks, Nokia Pty Ltd
> Brisbane Office

-----------------------------------------------
Israel Brewster
Computer Support Technician II
Frontier Flying Service Inc.
5245 Airport Industrial Rd
Fairbanks, AK 99709
(907) 450-7250 x293
-----------------------------------------------



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