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https://issues.apache.org/jira/browse/HIVE-8840?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14212625#comment-14212625
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Xuefu Zhang commented on HIVE-8840:
-----------------------------------
Patch looks good. Originally I thought we need to make changes to ExplainTask,
but this is inituitive and solves the problem. I only have a minor comment on
RB.
> Print prettier Spark work graph after HIVE-8793 [Spark Branch]
> --------------------------------------------------------------
>
> Key: HIVE-8840
> URL: https://issues.apache.org/jira/browse/HIVE-8840
> Project: Hive
> Issue Type: Sub-task
> Components: Spark
> Reporter: Xuefu Zhang
> Assignee: Jimmy Xiang
> Fix For: spark-branch
>
> Attachments: HIVE-8840.1-spark.patch
>
>
> Because of HIVE-8793, the work graph for Spark is possibly modified by
> SplitSparkWorkResolver. Original:
> {code}
> Spark
> Edges:
> Reducer 2 <- Map 1 (SORT, 1)
> Reducer 3 <- Reducer 2 (GROUP, 1)
> Reducer 4 <- Reducer 2 (GROUP, 1)
> {code}
> New graph
> {code}
> Spark
> Edges:
> Reducer 3 <- Reducer 5 (GROUP, 1)
> Reducer 4 <- Reducer 6 (GROUP, 1)
> Reducer 5 <- Map 1 (SORT, 1)
> Reducer 6 <- Map 1 (SORT, 1)
> {code}
> where Reducer2 was splitted into Reducer5 and Reducer6.
> Two types of ordering can be considered:
> 1. Topological order
> {code}
> Spark
> Edges:
> Reducer 5 <- Map 1 (SORT, 1)
> Reducer 6 <- Map 1 (SORT, 1)
> Reducer 3 <- Reducer 5 (GROUP, 1)
> Reducer 4 <- Reducer 6 (GROUP, 1)
> {code}
> 2. DFS
> {code}
> Spark
> Edges:
> Reducer 5 <- Map 1 (SORT, 1)
> Reducer 3 <- Reducer 5 (GROUP, 1)
> Reducer 6 <- Map 1 (SORT, 1)
> Reducer 4 <- Reducer 6 (GROUP, 1)
> {code}
> Both seems better, though topolical seems more suitable for a graph. Please
> feel free to create a patch on trunk if needed.
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