Hi All:
Please indulge an embarrassing question for which I am sure there is a simple
answer.
Consider an aggregator which takes input like:
A A 2
A B 5
A C 10
A A 4
A B 9
A D 5
and returns
A A 6
A B 14
A C 10
A D 5
A 35
I've been using the aggregation classes to do the above very easily. My
question goes more to what are best practices in representing the output. The
solution I've used is to create new keys by concat-ing the various values, like
this:
public class distinctRowAggregatorDescriptor extends
ValueAggregatorBaseDescriptor
{
public ArrayList<Entry> generateKeyValPairs(Object key, Object val) {
String input [] = val.toString().split("\t");
ArrayList<Entry> retv = new ArrayList<Entry>();
.
.
retv.add(generateEntry(LONG_VALUE_SUM, input[0]+"_"+input[1],
(int)input[2]));
return retv;
}
}
This works just fine, and creates output that looks like:
A_B 14
and then I have to make a pass across the output data to split the "keys" up
to make something suitable for loading into a database. In my little prototype
the split apart pass is just a script.
The approach above, which does produce correct results, seems inherently
misguided/broken with respect to getting the final output formatted correctly.
Can somebody buy me a vowel and show me how to go straight to a multiple
column output format and avoid the embarrasing non-parallel split to produce my
load files?
Thanks,
C G
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