[ https://issues.apache.org/jira/browse/PIG-490?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Thejas M Nair updated PIG-490: ------------------------------ Fix Version/s: 0.9.0 (was: 0.8.0) Moving fix version to 0.9. I am not likely to be able to fix this in time for 0.8 . > Combiner not used when group elements referred to in tuple notation instead > of flatten. > --------------------------------------------------------------------------------------- > > Key: PIG-490 > URL: https://issues.apache.org/jira/browse/PIG-490 > Project: Pig > Issue Type: Bug > Affects Versions: 0.2.0 > Reporter: Alan Gates > Assignee: Thejas M Nair > Fix For: 0.9.0 > > > Given a query like: > {code} > A = load 'myfile'; > B = group A by ($0, $1); > C = foreach B generate group.$0, group.$1, COUNT(A); > {code} > The combiner will not be invoked. But if the last line is changed to: > {code} > C = foreach B generate flatten(group), COUNT(A); > {code} > it will be. The reason for the discrepancy is because the CombinerOptimizer > checks that all of the projections are simple. If not, it does not use the > combiner. group.$0 is not a simple projection, so this is failed. However, > this is a common enough case that the CombinerOptimizer should detect it and > still use the combiner. -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online.