It's ok. The Pig object model is quite powerful, but can be hard to grok at first. Don't be afraid to ask questions, though it helps to post a full script that reproduces the problem, and any relevant stack traces. :)
2012/5/17 John Morrison <[email protected]> > Thanks Jonathan, that was the key. I have been trying for several days > to solve this simple problem. > > I guess I need to RTFM a little closer. :) > > -John > > On Thu, May 17, 2012 at 9:07 PM, Jonathan Coveney <[email protected] > >wrote: > > > Ah, this is the most common error for people starting out :) > > > > SUM is a function which takes a bag (not a relation or a column) and > > returns the sum of the elements in that bag. > > > > Try: > > > > A = LOAD 'v.log' AS (a:double) ; > > B = foreach (group A all) generate SUM(A) ; > > dump B; > > > > 2012/5/17 John Morrison <[email protected]> > > > > > OK. I have simplified the script and tried 2 different ways without > > > success: > > > > > > 1) B = foreach A generate flatten($0), SUM($0.a) ; > > > 2) B = foreach A generate flatten($0), SUM(a) ; > > > > > > Which both produce different errors(see below)? > > > > > > Thanks, > > > > > > John > > > > > > Data: > > > cat v.log > > > > > > 1 > > > 2 > > > 3 > > > 4 > > > > > > > > > Complete script 1 with error: > > > > > > A = LOAD 'v.log' AS (a:double) ; > > > dump A; > > > B = foreach A generate flatten($0), SUM($0.a) ; > > > dump B; > > > > > > Error for above script: > > > 2012-05-17 20:54:11,836 [main] ERROR org.apache.pig.tools.grunt.Grunt - > > > ERROR 1000: Error during parsing. Invalid alias: a in null > > > > > > > > > Complete script 2 with error: > > > > > > > > > A = LOAD 'v.log' AS (a:double) ; > > > dump A; > > > B = foreach A generate flatten($0), SUM(a) ; > > > dump B; > > > > > > > > > 2012-05-17 20:56:11,795 [main] ERROR org.apache.pig.tools.grunt.Grunt - > > > ERROR 1045: Could not infer the matching function for > > > org.apache.pig.builtin.SUM as multiple or none of them fit. Please use > an > > > explicit cast. > > > > > > > > > > > > > > > On Thu, May 17, 2012 at 6:31 PM, Jonathan Coveney <[email protected] > > > >wrote: > > > > > > > I imagine the issue is that you're not giving it a bag... can you > paste > > > the > > > > whole script? That said, my guess is that this comes right after a > > group > > > > by, and that the following will fix it: > > > > > > > > C = foreach B generate flatten($0), sum($0.lane_nbr) ; > > > > > > > > but I'd need the whole script to be sure > > > > > > > > 2012/5/17 John Morrison <[email protected]> > > > > > > > > > OK. New problem with needing to use explicit cast? > > > > > > > > > > Could you give me syntax for explict cast? > > > > > > > > > > 2012-05-17 15:29:13,769 [main] ERROR > > org.apache.pig.tools.grunt.Grunt - > > > > > ERROR 1046: Multiple matching functions for > > org.apache.pig.builtin.SUM > > > > with > > > > > input schema: ({{bytearray}}, {{double}}). Please use an explicit > > cast. > > > > > > > > > > > > > > > > > > > > On Thu, May 17, 2012 at 11:42 AM, Prashant Kommireddi > > > > > <[email protected]>wrote: > > > > > > > > > > > UDFs are case-sensitive. It should be all caps - SUM > > > > > > > > > > > > Can you please give that a try? > > > > > > > > > > > > > > > > > > On May 17, 2012, at 8:24 AM, John Morrison < > > > [email protected]> > > > > > > wrote: > > > > > > > > > > > > > Hi, > > > > > > > > > > > > > > I am new to ping and am unable to use pig builtin functions > > (please > > > > see > > > > > > > details below). > > > > > > > > > > > > > > Is this a CLASSPATH issue? > > > > > > > > > > > > > > Any ideas on how to resolve? > > > > > > > > > > > > > > Thanks, > > > > > > > > > > > > > > John > > > > > > > > > > > > > > Details > > > > > > > > > > > > > > ### Line in pig script causing issue > > > > > > > C = foreach B generate flatten($0), sum(lane_nbr) ; > > > > > > > > > > > > > > ### Error message > > > > > > > 2012-05-17 11:15:41,673 [main] ERROR > > > org.apache.pig.tools.grunt.Grunt > > > > > - \ > > > > > > > ERROR 1070: Could not resolve sum using imports: [, > > > > > > > org.apache.pig.builtin., org.apache.pig.impl.builtin.] > > > > > > > > > > > > > > pig -version > > > > > > > Apache Pig version 0.8.1-cdh3u3 (rexported) > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > John Morrison > > > > > > > > > > > > > > > > > > > > > -- > > > John Morrison > > > > > > > > > -- > John Morrison >
