Hi, I am using Cloudera release cdh3u3, which has the hive 0.71 version.
I am trying to write a hive UDF function as to calculate the moving sum. Right
now, I am having trouble to get the constrant value passed in in the
initialization stage.
For example, let's assume the function is like the following format:
msum(salary, 10) --------- salary is a int type column
which means the end user wants to calculate the last 10 rows of salary.
I kind of know how to implement this UDF. But I have one problem right now.
1) This is not a UDAF, as each row will return one data back as the moving
sum.2) I create an UDF class extends from the GenericUDF.3) I can get the
column type from the ObjectInspector[] passed to me in the initialize() method
to verify that 'salary' and 10 both needs to be numeric type (later one needs
to be integer)4) But I also want to get the real value of 10, in this case, in
the initialize() stage, so I can create the corresponding data structure based
on the value end user specified here.5) I looks around the javadoc of
ObjectInspector class. I know at run time the real class of the 2nd parameter
is WritableIntObjectInspector. I can get the type, but how I can get the real
value of it?6) This is kind of ConstantsObjectInspector, should be able to give
the value to me, as it already knows the type is int. What how?7) I don't want
to try to get the value at the evaluate stage. Can I get this value at the
initialize stage?
Thanks
Yong
