無法推斷COUNT函數

我正在嘗試編寫一個拉丁腳本來拉取我過濾的數據集的數量。無法推斷COUNT函數

這裏的腳本至今：

/* scans by title */ 

scans   = LOAD '/hive/scans/*' USING PigStorage(',') AS (thetime:long,product_id:long,lat:double,lon:double,user:chararray,category:chararray,title:chararray); 
productscans = FILTER scans BY (title MATCHES 'proactiv'); 
scancount  = FOREACH productscans GENERATE COUNT($0); 
DUMP scancount;

出於某種原因，我得到的錯誤：

Could not infer the matching function for org.apache.pig.builtin.COUNT as multiple or none of them fit. Please use an explicit cast.

什麼我錯在這裏做什麼？我假設它與我傳入的字段的類型有關，但似乎無法解決此問題。

TIA，傑森

來源

2012-03-22 JasonA

這是你在找什麼（所有組將一切準備一個袋子，然後計算項目）：

scans   = LOAD '/hive/scans/*' USING PigStorage(',') AS (thetime:long,product_id:long,lat:double,lon:double,user:chararray,category:chararray,title:chararray); 
productscans = FILTER scans BY (title MATCHES 'proactiv'); 
grouped   = GROUP productscans ALL; 
count   = FOREACH grouped GENERATE COUNT(productscans); 
dump count;

來源

2012-03-23 01:58:52

就是這樣（減去「FOREACH克」應該是「FOREACH分組」） - 謝謝克里斯！ – JasonA 2012-03-23 14:02:56

編輯，感謝您的審查 – 2012-03-23 14:32:18

也許

/* scans by title */ 

scans   = LOAD '/hive/scans/*' USING PigStorage(',') AS (thetime:long,product_id:long,lat:double,lon:double,user:chararray,category:chararray,title:chararray); 
productscans = FILTER scans BY (title MATCHES 'proactiv'); 
scancount  = FOREACH productscans GENERATE COUNT(productscans); 
DUMP scancount;

來源

2012-03-22 19:31:44 whoisjake

感謝傑克 - 不幸的是，沒有運氣。這給了我：'無效的標量投影：productscans：一列需要從一個關係投影，它被用作標量' – JasonA 2012-03-22 20:25:25

COUNT 需要前面的GROUP ALL語句用於全局計數和GROUP BY語句用於組計數。

您可以使用以下任何：

scans   = LOAD '/hive/scans/*' USING PigStorage(',') AS (thetime:long,product_id:long,lat:double,lon:double,user:chararray,category:chararray,title:chararray); 
productscans = FILTER scans BY (title MATCHES 'proactiv'); 
grouped   = GROUP productscans ALL; 
count   = FOREACH grouped GENERATE COUNT(productscans); 
DUMP scancount;

或者

scans   = LOAD '/hive/scans/*' USING PigStorage(',') AS (thetime:long,product_id:long,lat:double,lon:double,user:chararray,category:chararray,title:chararray); 
productscans = FILTER scans BY (title MATCHES 'proactiv'); 
grouped   = GROUP productscans ALL; 
count   = FOREACH grouped GENERATE COUNT($1); 
DUMP scancount;

來源

2014-11-20 07:29:15 Sanjiv

無法推斷COUNT函數

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