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From "Fabian Hueske (JIRA)" <j...@apache.org>
Subject [jira] [Created] (FLINK-1664) Fix sorting on POJO fields
Date Mon, 09 Mar 2015 17:07:38 GMT
Fabian Hueske created FLINK-1664:

             Summary: Fix sorting on POJO fields
                 Key: FLINK-1664
                 URL: https://issues.apache.org/jira/browse/FLINK-1664
             Project: Flink
          Issue Type: Bug
          Components: JobManager
    Affects Versions: 0.8.0, 0.9
            Reporter: Fabian Hueske

Flink's groupSort, partitionSort, and outputSort operators allow to sort partitions or groups
of a DataSet.

If the sort is defined on a POJO field, the sort order is not well defined. Internally, the
POJO is recursively decomposed into atomic fields (primitives or generic types) and sorted
by sorting these atomic fields. Thereby, the order of these atomic fields is not well defined
(I believe it is lexicographic order of the POJO's member names).

IMO, the best approach is to forbid sorting on POJO types for now. Instead, it is always possible
to select the nested fields of the POJO that should be used for sorting. Later we can relax
this restriction.

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