datafu-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Eyal Allweil (JIRA)" <j...@apache.org>
Subject [jira] [Created] (DATAFU-130) Add left outer join macro described in the DataFu guide
Date Tue, 12 Sep 2017 13:36:08 GMT
Eyal Allweil created DATAFU-130:
-----------------------------------

             Summary: 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


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)

Mime
View raw message