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https://issues.apache.org/jira/browse/FLINK-6097?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15930890#comment-15930890
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ASF GitHub Bot commented on FLINK-6097:
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Github user sunjincheng121 commented on the issue:
https://github.com/apache/flink/pull/3560
HI, @KurtYoung Thanks for your attention to this PR. Good question, the
purpose of this change is just like this JIRA's description:
I want `ProjectionTranslator # identifyFieldReferences` to guaranteed the
order of the extracted field references same as input order. using `Set` just
want to eliminate duplicate field references, and `List` also can do this, it
is no harm to keep the `ProjectionTranslator # identifyFieldReferences`
method's output order consistent with input.
If the disorder results of `ProjectionTranslator #
identifyFieldReferences` can work, then the orderly results must also work very
well, because the order is also a situation of disorder.
What to you think?
Thanks,
SunJincheng
> Guaranteed the order of the extracted field references
> ------------------------------------------------------
>
> Key: FLINK-6097
> URL: https://issues.apache.org/jira/browse/FLINK-6097
> Project: Flink
> Issue Type: Improvement
> Components: Table API & SQL
> Reporter: sunjincheng
> Assignee: sunjincheng
>
> The current `ProjectionTranslator # identifyFieldReferences` method uses the`
> Set` temporary save field, when the number of elements in the Set is less
> than 5, the Set takes the Se1, Se2, Se3, Se4 data structures. When the number
> of elements is greater than or equal to 5, the Set takes HashSet #
> HashTrieSet and which will cause the data to be out of order. although the
> out of order is also working, but I think the order is better than out of
> order. So I want to improve it,Orderly extraction field.i.e.Guaranteed the
> order of the extracted field references as input order.
> e.g.:
> Add the following elements in turn:
> {code}
> A, b, c, d, e
> Set (a)
> Class scala.collection.immutable.Set $ Set1
> Set (a, b)
> Class scala.collection.immutable.Set $ Set2
> Set (a, b, c)
> Class scala.collection.immutable.Set $ Set3
> Set (a, b, c, d)
> Class scala.collection.immutable.Set $ Set4
> Set (e, a, b, c, d) -> I want (a, b, c, d, e)
> Class scala.collection.immutable.HashSet $ HashTrieSet
> {code}
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