Question

cust_joined = JOIN cust_filtered BY (LOW, HIGH, NORMAL), cust_conversion BY (Low, High, Normal);

当所有这些字段的数据类型都是chararray时。

cust_filtered包括以下条目 - 我存储了这个关系，这些关系存在于该文件中：

cust_id           Val1      Val2     Year      Low  High  Normal  Prod-code
1925635222        16.2      61.2     2013      null null  <=6.9   1234548-5
9253821456        16.8      65.8     2014      null null  <7.0    4548567-9

cust_conversion中的示例条目 - 我存储了这个关系，这些关系存在于该文件中：

Low     High   Normal     Cust-Session     Price
null    null    <=6.9      ABC-1234        16.9
null    null    <=7.0      PQR-4567        87.0

不幸的是，cust_joined关系为空。任何有关这方面的帮助都会很棒

Answer 1

我不知道为什么它不适合你，它对我有用。你能粘贴猪脚吗。

cust_filtered = LOAD 'cust_filtered.txt' USING PigStorage(' ') AS(cust_id:long,Val1:float,Val2:float,Year:chararray, LOW:chararray, HIGH:chararray, NORMAL:chararray, Prod_code:chararray);
cust_conversion = LOAD 'cust_conversion.txt' USING PigStorage(' ') AS (Low:chararray, High:chararray, Normal:chararray, Cust_Session:chararray, Price:float);
cust_joined = JOIN cust_filtered BY (LOW, HIGH, NORMAL), cust_conversion BY (Low, High, Normal);
DUMP cust_joined;

OUTPUT:
(1925635222,16.2,61.2,2013,null,null,<=6.9,1234548-5,null,null,<=6.9,ABC-1234,16.9)

Answer 2

我假设你的数据中有null，你有实际的猪值null，这是正确的吗？

如果是这样，那么这就是原因，因为猪内部联接忽略了空键：

The JOIN operator always performs an inner join. Inner joins ignore null keys, so it makes sense to filter them out before the join.

请参阅http://pig.apache.org/docs/r0.12.0/basic.html#join-inner

如果这些是以"null"作为值的字符集，那么这应该基本上起作用，如另一个答案所述。

Apache Pig join返回空关系

2 个答案: