Optimize CASE expressions by removing WHEN false branches #17628
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Done! Can you also put a note in the PR description about what issue this fixes? |
| expr: None, | ||
| when_then_expr, | ||
| else_expr, | ||
| }) if !when_then_expr.is_empty() => { |
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Does this if guard make the below case arm unreachable?
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Yes, I think so
In general I think we could combine this branch with the one above (that checks for a single true clause) 🤔
So the logic would be
- if the
WHENexprs have any true or false literals - then rewrite the when_then expr, removing all
falseliterals and any arms after the firsttrue
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Thank you for this PR @SidChaudhary7 It seems there are a few failing tests -- can you look into them? |
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Once we merge this pr from @jackkleeman
If @SidChaudhary7 doesn't have time by tomorrow, I'll try and push it along |
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I don't mind taking it if you'd rather save your time for other things. Should be pretty straightforward for me since I did the previous WHEN TRUE PR. I'll leave that up to you @alamb |
Which issue does this PR close?
CASE WHEN false THEN ...#17590Expr::Caseexpressions #1693Rationale for this change
This PR implements an optimization for CASE expressions that removes unreachable
WHEN falsebranches and handlesWHEN truecases that make subsequent branches unreachable.For example:
Are there any user-facing changes?
No
This is my first contribution to DataFusion. Could a committer please trigger the CI tasks?
@alamb @andygrove @tustvold @ursabot