[freetds] sometimes sql is returning wrong data to application
Michal Seliga
michal.seliga at visicom.sk
Tue Dec 8 12:10:52 EST 2009
maybe its data related?
i constantly see this behaviour on one special result, nowhere else. btw its not
true that with debug version of libtdsodbc.so it gives always same string
appended to result, sometimes i get numbers....
i even tried to run appplication with valgrind, i got tons of errors, but
nothing what could be related to this
i will continue to search for its cause (or at least finda way how to reproduce
it properly), i will write when there will be some news
Frediano Ziglio wrote:
> MS renamed protocol so now "old" 8.0 is called 7.1 (continue to use 8.0
> for compatibility, 0.82 does not like 7.1 that much ;) ).
> I'm unable to reproduce your problem :(
> Very strange...
>
> freddy77
>
> Il giorno mar, 08/12/2009 alle 12.25 +0100, Michal Seliga ha scritto:
>> note that i use protocol version 8.0, not 7.x
>> to me it seems like some trailing 0 is missing... but i don't know where, i
>> don't understand code very well yet. i am going to try with cvs head version,
>> just in case that something new already fixed it
>>
>> Frediano Ziglio wrote:
>>> Well... the fact that occurs even in no-optimized code is fine, it means
>>> that is not a compiler or stack overflow problem. dummyTS is used for
>>> TEXT as timestamp... however timestamp is stored in another place... not
>>> into text buffer so how could dummyTS finish in text output buffer?
>>> Probably this is due to a varchar(max) field which is not supported by
>>> TDS protocol 7.1 so is returned like a TEXT field... have you other
>>> varchar/text fields in your result?
>>>
>>> I'll look deeper...
>>>
>>> freddy77
>>>
>>> Il giorno lun, 07/12/2009 alle 16.24 +0100, Michal Seliga ha scritto:
>>>> update - it happened with not optimized version of odbc library too :( only this
>>>> time garbage is not so random, if there is problem then there is text 'dummyTS'
>>>> appended to the end of result. i don't know where it came from
>>>>
>>>> Michal Seliga wrote:
>>>>> this problem is strange and i am not able to find out what happens
>>>>>
>>>>> i am using freetds + iodbc + qt and i am connection to mssql 2005 database
>>>>>
>>>>> *sometimes* i get wrong result from long varchar field. usually its good when
>>>>> query is launched at the beginning and it suddnly stop working when it happens
>>>>> later, when application is running for several minutes.
>>>>>
>>>>> when i compiled libtdsodbc.c without optimalizations (-O0 instead of -O2 in
>>>>> Makefile in odbc directory) then everything started to behave well and this
>>>>> didn't happened anymore
>>>>>
>>>>> it looks to me that something wasn't initialized properly with optimalizations
>>>>> enabled, but i am not able to find out what exactly it could be. when library
>>>>> was compiled with -O2 there were some warnings, maybe they were related, maybe
>>>>> not, i don't know.
>>>>>
>>>>> i tried to do some tracing, but with -O0 there is no problem and with -O2
>>>>> tracing is not very useful so i learned nothing.... i hope developers will have
>>>>> more luck
>>>>>
>>>>>
>>>>>
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