This has been reported as bug #489091 (https://bugs.launchpad.net/pbxt/+bug/489091 
)

On Nov 26, 2009, at 5:47 PM, Paul McCullagh wrote:

> Hi Kristian,
>
> This could be tricky. Basically, the way PBXT works this is  
> possible, because the statistics can depend on the speed of threads  
> running in the background.
>
> So this is likely to be a matter of timing.
>
> We will give this test a try, and see if we also get unstable results.
>
> Best regards,
>
> Paul
>
> On Nov 25, 2009, at 2:38 PM, Kristian Nielsen wrote:
>
>> Kristian Nielsen  writes:
>>
>>> We are working on merging latest MySQL (5.1.41) into MariaDB.
>>>
>>> After the merge, I see some test failures in the PBXT test suite.  
>>> See here:
>>
>> Ok, seems most of the PBXT failures are gone now. But one remains:
>>
>>   http://askmonty.org/buildbot/reports/cross_reference#branch=5.1- 
>> merge&revision=&platform=debian5-i386- 
>> fulltest 
>> &dt 
>> = 
>> &bbnum 
>> = 
>> &typ 
>> = 
>> &info 
>> = 
>> &fail_name 
>> =pbxt.join_nested&fail_variant=&fail_info_short=&fail_info_full=
>>
>> (see end of mail for diff).
>>
>> It looks like the test is not deterministic, and chooses a slightly  
>> different
>> execution plan between different test runs and platforms for the  
>> table t3 and
>> t4.
>>
>> Do you have any suggestions about how to deal with this?
>>
>> - Kristian.
>>
>>
>> CURRENT_TEST: pbxt.join_nested
>> --- /var/lib/buildbot/maria-slave/debian5-i386-fulltest/build/mysql- 
>> test/suite/pbxt/r/join_nested.result 2009-11-25 21:10:35.000000000  
>> +0300
>> +++ /var/lib/buildbot/maria-slave/debian5-i386-fulltest/build/mysql- 
>> test/suite/pbxt/r/join_nested.reject 2009-11-25 21:46:01.000000000  
>> +0300
>> @@ -1008,13 +1008,13 @@
>> 1 SIMPLE t1 ALL NULL NULL NULL NULL 3 100.00 Using where; Using  
>> join buffer
>> 1 SIMPLE t2 ALL NULL NULL NULL NULL 3 100.00 Using where
>> 1 SIMPLE t3 ALL NULL NULL NULL NULL 2 100.00 Using where
>> -1 SIMPLE t4 ref idx_b idx_b 5 test.t2.b 1 100.00 Using where
>> +1 SIMPLE t4 ref idx_b idx_b 5 test.t2.b 1 100.00
>> 1 SIMPLE t5 ALL idx_b NULL NULL NULL 3 100.00 Using where
>> 1 SIMPLE t6 ALL NULL NULL NULL NULL 3 100.00 Using where
>> 1 SIMPLE t7 ALL NULL NULL NULL NULL 2 100.00 Using where
>> 1 SIMPLE t8 ref idx_b idx_b 5 test.t5.b 1 100.00 Using where
>> 1 SIMPLE t9 ALL NULL NULL NULL NULL 3 100.00 Using where; Using  
>> join buffer
>> -Note 1003 select `test`.`t0`.`a` AS `a`,`test`.`t0`.`b` AS  
>> `b`,`test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t2`.`a`  
>> AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t3`.`a` AS  
>> `a`,`test`.`t3`.`b` AS `b`,`test`.`t4`.`a` AS `a`,`test`.`t4`.`b`  
>> AS `b`,`test`.`t5`.`a` AS `a`,`test`.`t5`.`b` AS  
>> `b`,`test`.`t6`.`a` AS `a`,`test`.`t6`.`b` AS `b`,`test`.`t7`.`a`  
>> AS `a`,`test`.`t7`.`b` AS `b`,`test`.`t8`.`a` AS  
>> `a`,`test`.`t8`.`b` AS `b`,`test`.`t9`.`a` AS `a`,`test`.`t9`.`b`  
>> AS `b` from `test`.`t0` join `test`.`t1` left join (`test`.`t2`  
>> left join (`test`.`t3` join `test`.`t4`) on(((`test`.`t4`.`b` =  
>> `test`.`t2`.`b`) and (`test`.`t3`.`a` = 1))) join `test`.`t5` left  
>> join (`test`.`t6` join `test`.`t7` left join `test`.`t8`  
>> on(((`test`.`t8`.`b` = `test`.`t5`.`b`) and (`test`.`t6`.`b` <  
>> 10)))) on(((`test`.`t7`.`b` = `test`.`t5`.`b`) and (`test`.`t6`.`b`  
>> >= 2)))) on((((`test`.`t3`.`b` = 2) or isnull(`test`.`t3`.`c`)) and  
>> ((`test`.`t6`.`b` = 2) or isnull(`test`.`t6`.`c`)) and  
>> ((`test`.`t5`.`b` = `test`.`t0`.`b`) or isnull(`test`.`t3`.`c`) or  
>> isnull(`test`.`t6`.`c`) or isnull(`test`.`t8`.`c`)) and  
>> (`test`.`t1`.`a` <> 2))) join `test`.`t9` where ((`test`.`t9`.`a` =  
>> 1) and (`test`.`t1`.`b` = `test`.`t0`.`b`) and (`test`.`t0`.`a` =  
>> 1) and ((`test`.`t2`.`a` >= 4) or isnull(`test`.`t2`.`c`)) and  
>> ((`test`.`t3`.`a` < 5) or isnull(`test`.`t3`.`c`)) and  
>> ((`test`.`t4`.`b` = `test`.`t3`.`b`) or isnull(`test`.`t3`.`c`) or  
>> isnull(`test`.`t4`.`c`)) and ((`test`.`t5`.`a` >= 2) or  
>> isnull(`test`.`t5`.`c`)) and ((`test`.`t6`.`a` >= 4) or  
>> isnull(`test`.`t6`.`c`)) and ((`test`.`t7`.`a` <= 2) or  
>> isnull(`test`.`t7`.`c`)) and ((`test`.`t8`.`a` < 1) or  
>> isnull(`test`.`t8`.`c`)) and ((`test`.`t9`.`b` = `test`.`t8`.`b`)  
>> or isnull(`test`.`t8`.`c`)))
>> +Note 1003 select `test`.`t0`.`a` AS `a`,`test`.`t0`.`b` AS  
>> `b`,`test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b`,`test`.`t2`.`a`  
>> AS `a`,`test`.`t2`.`b` AS `b`,`test`.`t3`.`a` AS  
>> `a`,`test`.`t3`.`b` AS `b`,`test`.`t4`.`a` AS `a`,`test`.`t4`.`b`  
>> AS `b`,`test`.`t5`.`a` AS `a`,`test`.`t5`.`b` AS  
>> `b`,`test`.`t6`.`a` AS `a`,`test`.`t6`.`b` AS `b`,`test`.`t7`.`a`  
>> AS `a`,`test`.`t7`.`b` AS `b`,`test`.`t8`.`a` AS  
>> `a`,`test`.`t8`.`b` AS `b`,`test`.`t9`.`a` AS `a`,`test`.`t9`.`b`  
>> AS `b` from `test`.`t0` join `test`.`t1` left join (`test`.`t2`  
>> left join (`test`.`t3` join `test`.`t4`) on(((`test`.`t4`.`b` =  
>> `test`.`t2`.`b`) and (`test`.`t3`.`a` = 1))) join `test`.`t5` left  
>> join (`test`.`t6` join `test`.`t7` left join `test`.`t8`  
>> on(((`test`.`t8`.`b` = `test`.`t5`.`b`) and (`test`.`t6`.`b` <  
>> 10)))) on(((`test`.`t7`.`b` = `test`.`t5`.`b`) and (`test`.`t6`.`b`  
>> >= 2)))) on((((`test`.`t3`.`b` = 2) or isnull(`test`.`t3`.`c`)) and  
>> ((`test`.`t6`.`b` = 2) or isnull(`test`.`t6`.`c`)) and  
>> ((`test`.`t5`.`b` = `test`.`t0`.`b`) or isnull(`test`.`t3`.`c`) or  
>> isnull(`test`.`t6`.`c`) or isnull(`test`.`t8`.`c`)) and  
>> (`test`.`t1`.`a` <> 2))) join `test`.`t9` where ((`test`.`t9`.`a` =  
>> 1) and (`test`.`t1`.`b` = `test`.`t0`.`b`) and (`test`.`t0`.`a` =  
>> 1) and ((`test`.`t2`.`a` >= 4) or isnull(`test`.`t2`.`c`)) and  
>> ((`test`.`t3`.`a` < 5) or isnull(`test`.`t3`.`c`)) and  
>> ((`test`.`t3`.`b` = `test`.`t4`.`b`) or isnull(`test`.`t3`.`c`) or  
>> isnull(`test`.`t4`.`c`)) and ((`test`.`t5`.`a` >= 2) or  
>> isnull(`test`.`t5`.`c`)) and ((`test`.`t6`.`a` >= 4) or  
>> isnull(`test`.`t6`.`c`)) and ((`test`.`t7`.`a` <= 2) or  
>> isnull(`test`.`t7`.`c`)) and ((`test`.`t8`.`a` < 1) or  
>> isnull(`test`.`t8`.`c`)) and ((`test`.`t9`.`b` = `test`.`t8`.`b`)  
>> or isnull(`test`.`t8`.`c`)))
>
>
>
> --
> Paul McCullagh
> PrimeBase Technologies
> www.primebase.org
> www.blobstreaming.org
> pbxt.blogspot.com
>
>
>
>
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--
Paul McCullagh
PrimeBase Technologies
www.primebase.org
www.blobstreaming.org
pbxt.blogspot.com