在 Pig 中过滤记录

Question

下面是数据

col1,col2,col3,col4,col5
------------------------
10,20,30,40,dollar
20,30,40,50,dollar
20,30,10,50,dollar
61,62,63,64,dollar
61,62,63,64,pound

col1,col2,col3 将形成唯一键的组合。用例是根据 col5 过滤数据。对于唯一键组合，我们需要过滤col5值为"dollar"的记录，只有相同的组合有"pound"值。

预期输出是

col1,col2,col3,col4,col5
------------------------
10,20,30,40,dollar
20,30,40,50,dollar
20,30,10,50,dollar
61,62,63,64,pound

由于 Pig 中没有像 Hive 那样的特殊运算符，因此如何进一步进行。

A = load 'test1.csv' using PigStorage(',') as (col1:int,col2:int,col3:int,col4:int,col5:chararray);
B = FILTER A BY col5 == 'pound';

Answer 1

获取所有'pound'的记录，然后获取所有'dollar'不匹配col5中id组合'pound'的记录。最后，把他们嫁出去... UNION.

B = FILTER A BY col5 == 'pound';
C = JOIN A BY (col1,col2,col3) LEFT OUTER,B BY (col1,col2,col3);
D = FILTER C BY (B::col1 is null);
E = FOREACH D GENERATE A::col1,A::col2,A::col3,A::col4,A::col5;
F = UNION B,E;
DUMP F;

输出

在 Pig 中过滤记录

Filter records in Pig

hadoop

apache-pig