後加入和GROUP BY我在新的豬,並試圖理解爲什麼我不能指望後加入和組:COUNT豬
A = LOAD 'mary' as (line);
B = LOAD 'mary' as (line);
wordsA = foreach A generate flatten(TOKENIZE(line)) as wordA;
grpdA = group wordsA by wordA;
cntdA = foreach grpdA generate group, COUNT(wordsA);
wordsB = foreach B generate flatten(TOKENIZE(line)) as wordB;
grpdB = group wordsB by wordB;
cntdB = foreach grpdB generate group, COUNT(wordsB), 'some text';
fltB = FILTER cntdB BY $1>1;
jnd = join cntdA by $1, fltB by $1;
jnd_n = foreach jnd generate $0;
grp = group jnd by $0;
out = foreach grp generate group, count(jnd_n);
dump jnd_n;
dump grp;
轉儲jnd_n:
(was)
(was)
(was)
(lamb)
(lamb)
(lamb)
(Mary)
(Mary)
(Mary)
轉儲GRP :
(was,{(was,2,was,2,some text),(was,2,Mary,2,some text),(was,2,lamb,2,some text)})
(Mary,{(Mary,2,was,2,some text),(Mary,2,Mary,2,some text),(Mary,2,lamb,2,some text)})
(lamb,{(lamb,2,was,2,some text),(lamb,2,Mary,2,some text),(lamb,2,lamb,2,some text)})
但我發現了錯誤:
Invalid scalar projection: jnd_n : A column needs to be projected from a relation for it to be used as a scalar
如果我試圖改變代碼:
out = foreach grp generate group, count(jnd_n.$0);
然後我發現了另一個錯誤:
Failed to generate logical plan. Nested exception: org.apache.pig.backend.executionengine.ExecException: ERROR 1070: Could not resolve count using imports: [, java.lang., org.apache.pig.builtin., org.apache.pig.impl.builtin.]
我知道我能做到這一點的另一種方式,但我想導致像這正是後做了兩次豬手術後JOIN和GROUP BY:
轉儲:
(was,3)
(lamb,3)
(Mary,3)
THX的答案,是COUNT是敏感的,卻得到了另一個錯誤: '錯誤org.apache.pig.tools.grunt.Grunt - 錯誤1045: <文件script.pig,24行,列34>無法推斷org.apache.pig.builtin.COUNT的匹配函數爲多個或不匹配。請使用明確的演員。「 – Dipas