Filtering a source and then merging the filtered rows only generates data from
one half of the filtering
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Key: PIG-2178
URL: https://issues.apache.org/jira/browse/PIG-2178
Project: Pig
Issue Type: Bug
Components: impl
Affects Versions: 0.8.1
Reporter: Derek Wollenstein
Pig is generating a plan that eliminates half of input data when using FILTER BY
To better illustarte, I created a small test case.
1. Create a file in HDFS called "/testinput"
The contents of the file should be:
"1\ta\taline\n1\tb\tbline"
2. Run the following pig script:
ORIG = LOAD '/testinput' USING PigStorage() AS (parent_id: chararray,
child_id:chararray, value:chararray);
-- Split into two inputs based on the value of child_id
A = FILTER ORIG BY child_id =='a';
B = FILTER ORIG BY child_id =='b';
-- Project out the column which chooses the correct data set
APROJ = FOREACH A GENERATE parent_id, value;
BPROJ = FOREACH B GENERATE parent_id, value;
-- Merge both datasets by parent id
ABMERGE = JOIN APROJ by parent_id FULL OUTER, BPROJ by parent_id;
-- Project the result
ABPROJ = FOREACH ABMERGE GENERATE APROJ::parent_id AS parent_id,
APROJ::value,BPROJ::value;
DUMP ABPROJ;
3. The resulting tuple will be
(1,aline,aline)
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