Incorrect column pruning after multiple JOIN operations
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Key: PIG-1327
URL: https://issues.apache.org/jira/browse/PIG-1327
Project: Pig
Issue Type: Bug
Affects Versions: 0.6.0
Reporter: Ankur
In a script with multiple JOIN and GROUP operations, the column pruner
incorrectly removes some of the fields that it shouldn't. Here is a script that
demonstrates the issue
= LOAD 'data1' USING PigStorage() AS (a:chararray, b:chararray, c:long);
B = LOAD 'data2' USING PigStorage() AS (x:chararray, y:chararray, z:long);
C = LOAD 'data3' using PigStorage() AS (d:chararray, e:chararray, f:chararray);
join1 = JOIN B by x, A by a;
filtered1 = FILTER join1 BY y == b;
InterimData = FOREACH filtered1 GENERATE a, b, c, y, z;
join2 = JOIN InterimData BY b LEFT OUTER, C BY d PARALLEL 2;
proj = FOREACH join2 GENERATE a,b,y,z,e,f;
TopNPrj = FOREACH proj GENERATE a, (( e is not null and e != '') ? e : 'None')
, z;
TopNDataGrp = GROUP TopNPrj BY (a, e) PARALLEL 2;
TopNDataSum = FOREACH TopNDataGrp GENERATE flatten(group) as (a, e),
SUM(TopNPrj.z) as views;
TopNDataRegrp = GROUP TopNDataSum BY (a) PARALLEL 2;
TopNDataCount = FOREACH TopNDataRegrp { OrderedData = ORDER TopNDataSum BY
views desc; LimitedData = LIMIT OrderedData 50; GENERATE LimitedData; }
TopNData = FOREACH TopNDataCount GENERATE flatten($0) as (a, e, views);
store TopNData into 'tmpTopN';
TopNData_stored = load 'tmpTopN' as (a:chararray, b:chararray, c:long);
joinTopNData = JOIN TopNData_stored BY (a,b) RIGHT OUTER, proj BY (a,b)
PARALLEL 2;
describe joinTopNData;
STORE joinTopNData INTO 'output';
The column 'f' from relation 'C' participating in the 2nd JOIN is missing from
the final join ouput
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