Use MultipleInputs and use two different mappers for the inputs. map1
should be IdentityMapper, mapper 2 should output key, value pairs where
value is a peudo marker value(same for all keys), which marks that the
value is null/empty. In the reducer just output the key/value pairs
which does not include the marker value in their values.
in your example suppose that we use -1 as a marker value, then in
mapper2, the output will be
4, -1
2, -1
and the reducer will get :
2, {1,3,5,-1}
3, {1,2}
4, {7,9,-1}
6, {3}
then reducer will output :
3, 1
3, 2
6, 3
Nir Zohar wrote:
Hi,
I would like your help with the below question.
I have 2 files: file1 (key, value), file2 (only key) and I need to exclude
all records from file1 that these key records not in file2.
1. The output format is key-value, not only keys.
2. The key is not primary key; hence it's not possible to have joined in the
end.
Can you assist?
Thanks,
Nir.
Example:
file1:
2,1
2,3
2,5
3,1
3,2
4,7
4,9
6,3
file2:
4
2
Output:
3,1
3,2
6,3
