[SPARK-13771][SQL][WIP] Eliminate child columns from project if the project with no references to its child #11602
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Member
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LGTM : ) |
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| // Eliminate the child from the Projects with no references to its child | ||
| case p @ Project(projectList, child) if p.references.intersect(child.outputSet).isEmpty => |
Contributor
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But this will change the number of rows right?
Member
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Yea. I think it is changed to 1 row. Indeed this causes problem.
Contributor
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This is an optimizable case, but I think we need a new relation that can produce n empty rows. |
Member
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You are right. |
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Test build #52735 has finished for PR 11602 at commit
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Contributor
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And looks like our data source can handle this case, they will take an empty array as |
viirya
changed the title
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I will change this later. Marked it as WIP now. |
Member
Author
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Rethink about this. I would like to close it for now. |
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JIRA: https://issues.apache.org/jira/browse/SPARK-13771
What changes were proposed in this pull request?
This is a corner case that a `Project` node can have no references to its child. E.g.,
We can actually replace the input with a dummy
OneRowRelation.This PR is inspired by #11599. The test case is slightly modified from #11599 too.
How was this patch tested?
ColumnPruningSuite.