pig是一种脚本语言，不像sql那样是关系语言，它非常适合使用foreach中嵌套了运算符的组。以下是解决方案：

A = LOAD 'input' USING PigStorage(',') AS (id:int, v1:float, v2:float);
B = GROUP A BY id; -- isolate all rows for the same id
C = FOREACH B { -- here comes the scripting bit
    elems = ORDER A BY v1 DESC; -- sort rows belonging to the id
    two = LIMIT elems 2; -- select top 2
    two_invers = ORDER two BY v1 ASC; -- sort in opposite order to bubble second value to the top
    second = LIMIT two_invers 1;
    GENERATE FLATTEN(group) as id, FLATTEN(second.v2);
};
DUMP C;

在您的示例中，id1有两行v1==0.2，但v2不同，因此id1的第二个值可以是0.1或0.3

A = LOAD 'input' USING PigStorage(',') AS (id:int, v1:int, v2:int);
B = ORDER A BY id ASC, v1 DESC;
C = FOREACH B GENERATE id, v2;
DUMP C;