ERROR 1066: Unable to open iterator for alias in certain fields, but works for others
alias, apache-pig, java, user-defined-functions
Solution
Could `date` be null some of the time? In your UDF there is a null check for the tuple but no check for `input.get(0)`
If this happens, it will hit your catch block and your UDF will error out. Could possibly be causing this error...
Problem
I am unable to use my udf on some fields, yet I can do it on others. If I use my first field, `ipAddress`, the udf works as intended. However, if I change it to be `date` I got the 1066 error. Here is my script. Pig Script that works and calls udf. ``` REGISTER myudfs.jar; DEFINE HOUR myudfs.HOUR; A = load 'access_log_Jul95' using PigStorage(' ') as (ip:chararray, dash1:chararray, dash2:chararray, date:chararray, date1:chararray, getRequset:chararray, location:chararray, http:chararray, code:int, port:int); B = FOREACH A GENERATE HOUR(ip); dump B; ``` Pig Script that does not work, and calls udf ``` REGISTER myudfs.jar; DEFINE HOUR myudfs.HOUR; A = load 'access_log_Jul95' using PigStorage(' ') as (ip:chararray, dash1:chararray, dash2:chararray, date:chararray, date1:chararray, getRequset:chararray, location:chararray, http:chararray, code:int, port:int); B = FOREACH A GENERATE HOUR(date); dump B; ``` Pig script that does work, but does not call udf ``` REGISTER myudfs.jar; DEFINE HOUR myudfs.HOUR; A = load 'access_log_Jul95' using PigStorage(' ') as (ip:chararray, dash1:chararray, dash2:chararray, date:chararray, date1:chararray, getRequset:chararray, location:chararray, http:chararray, code:int, port:int); B = FOREACH A GENERATE date; dump B; ``` Sample data ``` 199.72.81.55 - - [01/Jul/1995:00:00:01 -0400] "GET /history/apollo/ HTTP/1.0" 200 6245 ``` Java UDF ``` package myudfs; import java.io.IOException; import org.apache.pig.EvalFunc; import org.apache.pig.data.Tuple; import org.apache.pig.impl.util.WrappedIOException; public class HOUR extends EvalFunc<String> { @SuppressWarnings("deprecation") public String exec(Tuple input) throws IOException { if (input == null || input.size() == 0) return " "; try{ String str = (String)input.get(0); return str.substring(0, 1); }catch(Exception e){ throw WrappedIOException.wrap("Caught exception processing input row ", e); } } } ``` Error ``` ERROR org.apache.pig.tools.grunt.Grunt - ERROR 1066: Unable to open iterator for alias B ``` If there is anything else, let me know. I get this error running locally, and over map reduce.