0

我刚开始学习猪，我在重命名别名时遇到了问题。我想做的是读取一个文件，过滤它，然后自己加入它。我所做的是这样的：

register s3n://uw-cse-344-oregon.aws.amazon.com/myudfs.jar
raw = LOAD 's3n://uw-cse-344-oregon.aws.amazon.com/cse344-test-file' USING TextLoader as (line:chararray);
ntriples = foreach raw generate FLATTEN(myudfs.RDFSplit3(line)) as (subject:chararray,predicate:chararray,object:chararray);

ntriples2 = foreach raw generate FLATTEN(myudfs.RDFSplit3(line)) as (subject2:chararray,predicate2:chararray,object2:chararray);
X = FILTER ntriples BY (subject matches '.*business.*');
X2 = FILTER ntriples2 BY (subject2 matches '.*business.*');
joined= join X by subject, X2 by subject2;
joined = DISTINCT joined;
store joined into '/user/hadoop/join-results' using PigStorage();

如您所见，我两次读取并过滤文件，以便两个对每列有两个不同的别名。我怎样才能简单地复制过滤的集合并为其分配新的别名？这个手术原定需要 18 分钟，但需要 1.5 小时。

4

1 回答 1

3

我找到了答案：

X = FILTER ntriples BY (subject matches '.*rdfabout\\.com.*') PARALLEL 50;
y = foreach X generate subject as subject2, predicate as predicate2, object as object2 PARALLEL 50;

这就是复制 x 和更改别名的方式。

于 2013-06-05T21:09:26.103 回答