liukun4515 commented on code in PR #2819:
URL: https://github.com/apache/arrow-datafusion/pull/2819#discussion_r912441908
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datafusion/physical-expr/src/expressions/case.rs:
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@@ -291,12 +292,67 @@ impl PhysicalExpr for CaseExpr {
/// Create a CASE expression
pub fn case(
expr: Option<Arc<dyn PhysicalExpr>>,
- when_thens: &[WhenThen],
+ when_thens: Vec<WhenThen>,
else_expr: Option<Arc<dyn PhysicalExpr>>,
+ input_schema: &Schema,
) -> Result<Arc<dyn PhysicalExpr>> {
+ // all the result of then and else should be convert to a common data type,
+ // if they can be coercible to a common data type, return error.
+ let coerce_type = get_case_common_type(&when_thens, else_expr.clone(),
input_schema);
+ let (when_thens, else_expr) = match coerce_type {
+ None => Err(DataFusionError::Plan(format!(
+ "Can't get a common type for then {:?} and else {:?} expression",
+ when_thens, else_expr
+ ))),
+ Some(data_type) => {
+ // cast then expr
+ let left = when_thens
+ .into_iter()
+ .map(|(when, then)| {
+ let then = try_cast(then, input_schema,
data_type.clone()).unwrap();
+ (when, then)
+ })
+ .collect::<Vec<WhenThen>>();
+ let right = match else_expr {
+ None => None,
+ Some(expr) => Some(try_cast(expr, input_schema,
data_type.clone())?),
+ };
+ Ok((left, right))
+ }
+ }?;
+
Ok(Arc::new(CaseExpr::try_new(expr, when_thens, else_expr)?))
}
+fn get_case_common_type(
+ when_thens: &[WhenThen],
+ else_expr: Option<Arc<dyn PhysicalExpr>>,
Review Comment:
The reference is not work for this.
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