无法推断COUNT函数

我正在尝试编写一个拉丁脚本来拉取我过滤的数据集的数量。无法推断COUNT函数

这里的脚本至今：

/* 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;

出于某种原因，我得到的错误：

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

什么我错在这里做什么？我假设它与我传入的字段的类型有关，但似乎无法解决此问题。

TIA，杰森

来源

2012-03-22 JasonA

这是你在找什么（所有组将一切准备一个袋子，然后计算项目）：

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;

来源

2012-03-23 01:58:52

就是这样（减去“FOREACH克”应该是“FOREACH分组”） - 谢谢克里斯！ – JasonA 2012-03-23 14:02:56

编辑，感谢您的审查 – 2012-03-23 14:32:18

也许

/* 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;

来源

2012-03-22 19:31:44 whoisjake

感谢杰克 - 不幸的是，没有运气。这给了我：'无效的标量投影：productscans：一列需要从一个关系投影，它被用作标量' – JasonA 2012-03-22 20:25:25

COUNT 需要前面的GROUP ALL语句用于全局计数和GROUP BY语句用于组计数。

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;

来源

2014-11-20 07:29:15 Sanjiv

无法推断COUNT函数

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