Apache pig 在清管器中限制但不是顺序

我在PIG中使用

Limit

时遇到一个问题

Limit

的结果已排序，但我不希望对结果进行排序

根据网站上的示例：

A = LOAD 'data' AS (a1:int,a2:int,a3:int);

DUMP A;
(1,2,3)
(4,2,1)
(8,3,4)
(4,3,3)
(7,2,5)
(8,4,3)

使用

限制

X = LIMIT A 3;

DUMP X;
(1,2,3)
(4,3,3)
(7,2,5)

是否有可能在reuslt中显示前3行而不进行排序

(1,2,3)
(4,2,1)
(8,3,4)

我的代码如下：

A = LOAD '$input';
B = foreach A generate $s_field;
C = FILTER B BY $pattern;
D = FOREACH C {
            topnresult = LIMIT B $lines;
            GENERATE FLATTEN(topnresult);
        }
dump D;

---

非常感谢。

默认情况下，LIMIT将在内部执行ORDER命令，然后执行LIMIT命令，因此显然您将获得排序列表。有很多方法可以解决这个问题，其中一个选择是

input.txt

1       2       3
4       2       1
8       3       4
4       3       3
7       2       5
8       4       3

PigScript:

A = LOAD 'input.txt' AS (a1:int,a2:int,a3:int);
B = RANK A;
C = FILTER B BY rank_A<=3;
D = FOREACH C GENERATE a1,a2,a3;
DUMP D;

(1,2,3)
(4,2,1)
(8,3,4)

A = LOAD 'input.txt' AS (a1:int,a2:int,a3:int);
B = GROUP A ALL;
C = FOREACH B {
                top3list =  LIMIT A 3;
                GENERATE FLATTEN(top3list);
              }
DUMP C;

(1,2,3)
(4,2,1)
(8,3,4)

A = LOAD '$input';
B = foreach A generate $s_field;
C = FILTER B BY $pattern;
D = RANK C;
E = FILTER D BY rank_C<=$lines;
F = FOREACH E GENERATE $1..;
DUMP F;

选项2:

A = LOAD 'input.txt' AS (a1:int,a2:int,a3:int);
B = RANK A;
C = FILTER B BY rank_A<=3;
D = FOREACH C GENERATE a1,a2,a3;
DUMP D;

(1,2,3)
(4,2,1)
(8,3,4)

A = LOAD 'input.txt' AS (a1:int,a2:int,a3:int);
B = GROUP A ALL;
C = FOREACH B {
                top3list =  LIMIT A 3;
                GENERATE FLATTEN(top3list);
              }
DUMP C;

(1,2,3)
(4,2,1)
(8,3,4)

A = LOAD '$input';
B = foreach A generate $s_field;
C = FILTER B BY $pattern;
D = RANK C;
E = FILTER D BY rank_C<=$lines;
F = FOREACH E GENERATE $1..;
DUMP F;

输出：

A = LOAD 'input.txt' AS (a1:int,a2:int,a3:int);
B = RANK A;
C = FILTER B BY rank_A<=3;
D = FOREACH C GENERATE a1,a2,a3;
DUMP D;

(1,2,3)
(4,2,1)
(8,3,4)

A = LOAD 'input.txt' AS (a1:int,a2:int,a3:int);
B = GROUP A ALL;
C = FOREACH B {
                top3list =  LIMIT A 3;
                GENERATE FLATTEN(top3list);
              }
DUMP C;

(1,2,3)
(4,2,1)
(8,3,4)

A = LOAD '$input';
B = foreach A generate $s_field;
C = FILTER B BY $pattern;
D = RANK C;
E = FILTER D BY rank_C<=$lines;
F = FOREACH E GENERATE $1..;
DUMP F;

更新：解决方案1

A = LOAD '$input';
B = foreach A generate $s_field;
C = FILTER B BY $pattern;
D = GROUP C ALL;
E = FOREACH D {
            topnresult = LIMIT C $lines;
            GENERATE FLATTEN(topnresult);
        }
DUMP E;

解决方案2:

A = LOAD 'input.txt' AS (a1:int,a2:int,a3:int);
B = RANK A;
C = FILTER B BY rank_A<=3;
D = FOREACH C GENERATE a1,a2,a3;
DUMP D;

(1,2,3)
(4,2,1)
(8,3,4)

A = LOAD 'input.txt' AS (a1:int,a2:int,a3:int);
B = GROUP A ALL;
C = FOREACH B {
                top3list =  LIMIT A 3;
                GENERATE FLATTEN(top3list);
              }
DUMP C;

(1,2,3)
(4,2,1)
(8,3,4)

A = LOAD '$input';
B = foreach A generate $s_field;
C = FILTER B BY $pattern;
D = RANK C;
E = FILTER D BY rank_C<=$lines;
F = FOREACH E GENERATE $1..;
DUMP F;

A=加载“$input”；
B=每个生成$s_字段；
C=按$pattern筛选B；
D=等级C；
E=按秩_Cpig-x local-param input='input.txt'-param s_field='$0，$1，$2'-param pattern='$0使用pig和hadoop的版本是什么？你能粘贴你的示例数据和pig脚本吗？你能粘贴你的pig脚本吗？原因是你在混合这两种解决方案，请使用任何一种解决方案。过滤器stmt后不能使用嵌套FOREACH，bcoz嵌套FOREACH将仅适用于行李。请更新示例输入数据格式和$s_字段$pattern的值。我会帮你得到结果。有可能什么都不修改就得到结果吗？嗨，很抱歉最近回复了。结果似乎是按照另一个标准排序的，但我不理解排序方法。在我的程序中有两个属性，一个是仅显示前n行/结果，另一个是全部显示。对于“全部显示”属性，我使用
LIMIT C 9999999
显示所有结果。这是正确的方法吗？我们可以在PIG中使用通配符，例如
限制C*
？从结果来看，假设两个属性（top n和show all）的结果在开始时相同，不是吗？LIMIT的排序标准是什么？