Add Expr::Exists to represent EXISTS subquery expression
#2339
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alamb
approved these changes
Apr 25, 2022
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| let outer_query = LogicalPlanBuilder::from(bar) | ||
| .project(vec![col("a")])? | ||
| .filter(exists(subquery))? |
| // input: Arc::new(inputs[0].clone()), | ||
| // schema, | ||
| // })) | ||
| Err(DataFusionError::Plan("not implemented".to_string())) |
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Suggested change
| Err(DataFusionError::Plan("not implemented".to_string())) | |
| Err(DataFusionError::Plan("subquery support is not full implemented yet".to_string())) |
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I have now implemented this section of code, although it is not exercised by any tests yet
datafusion/expr/src/expr_fn.rs
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| @@ -180,6 +182,13 @@ pub fn approx_percentile_cont_with_weight( | |||
| } | |||
| } | |||
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| /// Create an EXISTS subquery expression | |||
| pub fn exists(subquery: LogicalPlan) -> Expr { | |||
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I wonder if this function should also be added to the prelude: https://github.com/apache/arrow-datafusion/blob/b890190a6521ab1e572184dcf6ea0a5afb3a47af/datafusion/core/src/prelude.rs#L33-L40
datafusion/expr/src/expr_fn.rs
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| @@ -180,6 +182,13 @@ pub fn approx_percentile_cont_with_weight( | |||
| } | |||
| } | |||
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| /// Create an EXISTS subquery expression | |||
| pub fn exists(subquery: LogicalPlan) -> Expr { | |||
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Maybe this function could take an Arc<LogicalPlan> so if someone already has one they can reuse it rather than making a copy to pass in here
Co-authored-by: Andrew Lamb <andrew@nerdnetworks.org>
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Which issue does this PR close?
Closes #2337 and is part of #2248
Rationale for this change
This is the first step towards supporting
EXISTSsubquery expressions. This work is partly based on work by @paveltiunov in cube-js@d14f0deWhat changes are included in this PR?
Expr::Exists(Subquery)expressionLogicalPlan::Subquery, although that wasn't strictly necessary just to supportEXISTSEXISTSusingLogicalPlanBuilderAre there any user-facing changes?
API change.