Question

尝试加入具有月份密钥数据集的月份中具有天数的一组。在我加入并尝试对集合执行FOREACH后，我得到一个错误：1066 ...后端错误：标量在输出中有多行。

这是一个具有相同问题的缩写集：

$ hadoop fs -cat DIM/\*
2011,01,31
2011,02,28
2011,03,31
2011,04,30
2011,05,31
2011,06,30
2011,07,31
2011,08,31
2011,09,30
2011,10,31
2011,11,30
2011,12,31

$ hadoop fs -cat ACCT/\*
2011,7,26,key1,23.25,2470.0
2011,7,26,key2,10.416666666666668,232274.08333333334
2011,7,26,key3,82.83333333333333,541377.25
2011,7,26,key4,78.5,492823.33333333326
2011,7,26,key5,110.83333333333334,729811.9166666667
2011,7,26,key6,102.16666666666666,675941.25
2011,7,26,key7,118.91666666666666,770896.75

然后是咕噜声：

grunt> DIM = LOAD 'DIM' USING PigStorage(',') AS (year:int, month:int, days:int);
grunt> ACCT = LOAD 'ACCT' USING PigStorage(',') AS (year:int, month:int, day: int, account:chararray, metric1:double, metric2:double);
grunt> AjD = JOIN ACCT BY (year,month), DIM  BY (year,month) USING 'replicated';
grunt> dump AjD;
...
(2011,7,26,key1,23.25,2470.0,2011,7,31)
(2011,7,26,key2,10.416666666666668,232274.08333333334,2011,7,31)
(2011,7,26,key3,82.83333333333333,541377.25,2011,7,31)
(2011,7,26,key4,78.5,492823.33333333326,2011,7,31)
(2011,7,26,key5,110.83333333333334,729811.9166666667,2011,7,31)
(2011,7,26,key6,102.16666666666666,675941.25,2011,7,31)
(2011,7,26,key7,118.91666666666666,770896.75,2011,7,31)
grunt> describe AjD;
AjD: {ACCT::year: int,ACCT::month: int,ACCT::day: int,ACCT::account: chararray,ACCT::metric1: double,ACCT::metric2: double,DIM::year: int,DIM::month: int,DIM::days: int}

grunt> FINAL = FOREACH AjD
>> GENERATE ACCT.year, ACCT.month, ACCT.account, (ACCT.metric2 / DIM.days);
grunt> dump FINAL;
...
ERROR org.apache.pig.tools.grunt.Grunt - ERROR 1066: Unable to open iterator for alias FINAL. Backend error : Scalar has more than one row in the output. 1st : (2011,7,26,key1,23.25,2470.0), 2nd :(2011,7,26,key2,10.416666666666668,232274.08333333334)

但是，如果我将其存储并重新加载以摆脱“加入”模式，它就会起作用：

grunt> STORE AjD INTO 'AjD' using PigStorage(',');
grunt> AjD2 = LOAD 'AjD' USING PigStorage(',') AS (year:int, month:int, day:int, account:chararray, metric1:double, metric2:double, year2:int, month2:int, days:int);

grunt> FINAL = FOREACH AjD2                                                                   
>> GENERATE year, month, account, (metric2 /days);         

grunt> dump FINAL;
...
(2011,7,key1,79.6774193548387)
(2011,7,key2,7492.712365591398)
(2011,7,key3,17463.782258064515)
(2011,7,key4,15897.526881720427)
(2011,7,key5,23542.319892473122)
(2011,7,key6,21804.5564516129)
(2011,7,key7,24867.637096774193)

有没有办法在连接集上迭代（FOREACH）而不存储和重新加载？

Answer 1

您是否尝试使用:: Operator指定要获取的列？

以(ACCT.metric2 / DIM.days)替换(ACCT::metric2 / DIM::days)。

e.g。

...
FINAL = FOREACH AjD
        GENERATE
             ACCT.year, ACCT.month, ACCT.account,(ACCT::metric2 / DIM::days);

迭代连接集后，PIG错误1066。

1 个答案: