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
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
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