On 10/26/2010 07:39 AM, Paweł Łoziński wrote: > Hi, > > the framework doesn't give you the first/last information about reduce > job you perform in your reducer. Just as the mapper doesn't give you > information whether the (key, value) pair passed to map function is > first/last for a given key. However you can workaround this by adding > special values to your data, e.g. <page><id>0</id>... and > <page><id>Long.MAX_VALUE</id>.... When you encounter those in your > reducer, you know you are at the beginning/end of your data and you > can emit <root> and </root>.
This wouldn't work, since it might as well be possible that the last value isn't Long.MAX_VALUE. I think I'm just adding the start- and end-tag afterwards. regards, Johannes
