alamb commented on code in PR #11553:
URL: https://github.com/apache/datafusion/pull/11553#discussion_r1684943750
##########
datafusion/sqllogictest/test_files/case.slt:
##########
@@ -50,3 +50,19 @@ SELECT CASE WHEN a > 2 THEN b END FROM foo
NULL
4
6
+
+# scalar or scalar (string)
Review Comment:
Could you also add a test where both arguments are scalars (like `CASE WHEN
1 > 2 THEN 'true' ELSE 'false')` ?
##########
datafusion/physical-expr/src/expressions/case.rs:
##########
@@ -344,6 +355,38 @@ impl CaseExpr {
internal_err!("predicate did not evaluate to an array")
}
}
+
+ fn scalar_or_scalar(&self, batch: &RecordBatch) -> Result<ColumnarValue> {
+ let return_type = self.data_type(&batch.schema())?;
+
+ // evaluate when expression
+ let when_value = self.when_then_expr[0].0.evaluate(batch)?;
+ let when_value = when_value.into_array(batch.num_rows())?;
+ let when_value = as_boolean_array(&when_value).map_err(|e| {
+ DataFusionError::Context(
+ "WHEN expression did not return a BooleanArray".to_string(),
+ Box::new(e),
+ )
+ })?;
+
+ // Treat 'NULL' as false value
+ let when_value = match when_value.null_count() {
+ 0 => Cow::Borrowed(when_value),
+ _ => Cow::Owned(prep_null_mask_filter(when_value)),
+ };
+
+ // evaluate then_value
+ let then_value = self.when_then_expr[0].1.evaluate(batch)?;
+ let then_value = Scalar::new(then_value.into_array(1)?);
+
+ // keep `else_expr`'s data type and return type consistent
+ let e = self.else_expr.as_ref().unwrap();
+ let expr = try_cast(Arc::clone(e), &batch.schema(),
return_type.clone())
+ .unwrap_or_else(|_| Arc::clone(e));
+ let else_ = Scalar::new(expr.evaluate(batch)?.into_array(1)?);
+
+ Ok(ColumnarValue::Array(zip(&when_value, &then_value, &else_)?))
Review Comment:
if the input is `ColumnarValue::Scalar` shouldn't the output also be a
`ColumnarValue::Scalar` (rather than a `ColumnarValue::Array`?)
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