在猪中创建一个庞大的过滤器

Question

我有这段代码。

large = load 'a super large file' 

CC = FILTER large BY $19 == 'abc OR $20 == 'abc' 
OR $19 == 'def' or $20 == 'def' ....; 

或条件的数量可能会上升到100甚至数千。

有没有更好的方法来做到这一点？

Answer 1

是的，将这些条件放在另一个文件中。将它加载到一个关系中，并将两个关系连接到该列上。如果必须在多列上过滤，则创建与条件一样多的过滤器文件。下面是2列

large = load 'a super large file' 
filter1 = load 'file with values needed to compare with $19'; 
filter2 = load 'file with values needed to compare with $20'; 
f1 = JOIN large BY $19,filter1 BY $0; 
f2 = JOIN large BY $20,filter2 BY $0; 
final = UNION f1,f2; 
DUMP final; 

你或许可以使用多列1个过滤文件和加入那些得到不同的过滤效果，然后就工会的关系。

large = load 'a super large file' 
filter_file = load 'file with values in different columns'; 

f1 = JOIN large BY $19,filter_file BY $0; 
f2 = JOIN large BY $20,filter_file BY $1; 
final = UNION f1,f2; 
DUMP final;