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ASF GitHub Bot commented on FLINK-1656: --------------------------------------- Github user asfgit closed the pull request at: https://github.com/apache/flink/pull/525 > Filtered Semantic Properties for Operators with Iterators > --------------------------------------------------------- > > Key: FLINK-1656 > URL: https://issues.apache.org/jira/browse/FLINK-1656 > Project: Flink > Issue Type: Bug > Components: Documentation > Affects Versions: 0.9 > Reporter: Fabian Hueske > Assignee: Fabian Hueske > Priority: Critical > > The documentation of ForwardedFields is incomplete for operators with > iterator inputs (GroupReduce, CoGroup). > This should be fixed ASAP, because it can lead to incorrect program execution. > The conditions for forwarded fields on operators with iterator input are: > 1) forwarded fields must be emitted in the order in which they are received > through the iterator > 2) all forwarded fields of a record must stick together, i.e., if your > function builds record from field 0 of the 1st, 3rd, 5th, ... and field 1 of > the 2nd, 4th, ... record coming through the iterator, these are not valid > forwarded fields. > 3) it is OK to completely filter out records coming through the iterator. > The reason for these conditions is that the optimizer uses forwarded fields > to reason about physical data properties such as order and grouping. Mixing > up the order of records or emitting records which are composed from different > input records, might destroy a (secondary) order or grouping. -- This message was sent by Atlassian JIRA (v6.3.4#6332)