2014年5月1日
Pig Latin JOIN (inner) 与JOIN (outer)的区别
摘要： 1、内连接(自然连接): 只有两个表相匹配的行才能在结果集中出现 2、外连接: 包括 （1）左外连接(左边的表不加限制) （2）右外连接(右边的表不加限制) （3）全外连接(左右两表都不加限制) 3. 例子 a.txt1 2 3 4 2 18 3 44 3 37 2 58 4 3b.... 阅读全文
posted @ 2014-05-01 19:35 JamesFan 阅读(343) 评论(0) 推荐(0)
Pig Flatten 解包操作，解元组
摘要： Flatten OperatorThe FLATTEN operator looks like a UDF syntactically, but it is actually an operator that changes the structure of tuples and bags in a... 阅读全文
posted @ 2014-05-01 13:19 JamesFan 阅读(423) 评论(0) 推荐(0)
Pig FOREACH 嵌套循环
摘要： Example: Nested BlockSuppose we have relations A and B. Note that relation B contains an inner bag.A = LOAD 'data' AS (url:chararray,outlink:chararray... 阅读全文
posted @ 2014-05-01 12:11 JamesFan 阅读(636) 评论(0) 推荐(0)