[Monetdb-developers] Another big group by query

Martin Kersten Martin.Kersten at cwi.nl
Mon Apr 13 12:29:48 CEST 2009


Stefan de Konink wrote:
> Stefan Manegold wrote:
>> counting the size of 362105182 groups over 365652137 BUNs ...
>>
>> The sum of all shown times is "only" 116865583 usec (i.e., just under 2 min).
> 
> Then it is likely the output misses the last actual 'big time consumer', 
> while Martin suggested it would show that event.
> 
Profiling instructions is an expensive operation and only enabled
upon request. Moreover, you need to read the system counters before
and after the instruction. This means when you start the stethoscope
you will only see the results as of the *next* MAL instruction being
executed.




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