Hadoop Pig：使用 STARTSWITH 显示条目

Question

我在使用 STARTSWITH 字符串函数时遇到问题。我想显示 System_Period 中以 20040

开头的所有记录

transactions = LOAD '/home/cloudera/datasets/assignment2/Transactions.csv'
USING PigStorage(',') AS (Branch_Number:int, Contract_Number:int,
Customer_Number:int,Invoice_Date:chararray, Invoice_Number:int,
Product_Number:int, Sales_Amount:double, Employee_Number:int,
Service_Date:chararray, System_Period:int);

sysGroup = GROUP transactions BY System_Period;

sysFilter = FILTER sysGroup BY STARTSWITH(transactions.System_Period, 20040);

DUMP sysFilter;

我收到的错误是

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

Answer 1

STARTSWITH只是用来比较一个tuple1和tuple2，检查tuple1是否包含tuple2。您不能将关系或包传递给它。还有一件事要注意的是它只接受 String(chararray) 而不是整数。在 GROUP BY 之前过滤以 20040 开头的 system_period 并将 system_period 加载为字符数组，然后根据需要在过滤器之后将其投射。

transactions = LOAD '/home/cloudera/datasets/assignment2/Transactions.csv'
USING PigStorage(',') AS (Branch_Number:int, Contract_Number:int,
Customer_Number:int,Invoice_Date:chararray, Invoice_Number:int,
Product_Number:int, Sales_Amount:double, Employee_Number:int,
Service_Date:chararray, System_Period:chararray);
sysFilter = FILTER transactions BY STARTSWITH(System_Period, '20040');

Else after GROUP BY FLATTEN 结果然后 filter

transactions = LOAD '/home/cloudera/datasets/assignment2/Transactions.csv'
USING PigStorage(',') AS (Branch_Number:int, Contract_Number:int,
Customer_Number:int,Invoice_Date:chararray, Invoice_Number:int,
Product_Number:int, Sales_Amount:double, Employee_Number:int,
Service_Date:chararray, System_Period:chararray);
sysGroup = GROUP transactions BY System_Period;
flatres = FOREACH sysGroup GENERATE group,FLATTEN(transactions);
sysFilter = FILTER flatres BY STARTSWITH(System_Period, '20040');

Hadoop Pig：使用 STARTSWITH 显示条目

Hadoop Pig: Show entries using STARTSWITH

hadoop

apache-pig