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Eyal Allweil commented on DATAFU-130: ------------------------------------- I think this is a good Jira issue to put in the [Apache Help Wanted site|https://helpwanted.apache.org/]. If there's no objection, I'll add it there. > Add left outer join macro described in the DataFu guide > ------------------------------------------------------- > > Key: DATAFU-130 > URL: https://issues.apache.org/jira/browse/DATAFU-130 > Project: DataFu > Issue Type: New Feature > Reporter: Eyal Allweil > Labels: macro, newbie > > In our > [guide|http://datafu.incubator.apache.org/blog/2013/09/04/datafu-1-0.html], a > macro is described for making a three-way left outer join conveniently. We > can add this macro to DataFu to make it even easier to use. > The macro's code is as follows: > {noformat} > DEFINE left_outer_join(relation1, key1, relation2, key2, relation3, key3) > returns joined { > cogrouped = COGROUP $relation1 BY $key1, $relation2 BY $key2, $relation3 BY > $key3; > $joined = FOREACH cogrouped GENERATE > FLATTEN($relation1), > FLATTEN(EmptyBagToNullFields($relation2)), > FLATTEN(EmptyBagToNullFields($relation3)); > } > (we would obviously want to add a test for this, too) > {noformat} -- This message was sent by Atlassian JIRA (v6.4.14#64029)