jorgecarleitao commented on a change in pull request #8749:
URL: https://github.com/apache/arrow/pull/8749#discussion_r529768333
##########
File path: rust/datafusion/src/sql/planner.rs
##########
@@ -446,6 +446,42 @@ impl<'a, S: SchemaProvider> SqlToRel<'a, S> {
SQLExpr::Wildcard => Ok(Expr::Wildcard),
+ SQLExpr::Case {
+ operand,
+ conditions,
+ results,
+ else_result,
+ } => {
+ let expr = if let Some(e) = operand {
+ Some(Box::new(self.sql_to_rex(e, schema)?))
+ } else {
+ None
+ };
+ let when_expr = conditions
+ .iter()
+ .map(|e| self.sql_to_rex(e, schema))
+ .collect::<Result<Vec<_>>>()?;
+ let then_expr = results
+ .iter()
+ .map(|e| self.sql_to_rex(e, schema))
+ .collect::<Result<Vec<_>>>()?;
+ let else_expr = if let Some(e) = else_result {
+ Some(Box::new(self.sql_to_rex(e, schema)?))
+ } else {
+ None
+ };
Review comment:
Very clean implementation! 💯
##########
File path: rust/datafusion/tests/sql.rs
##########
@@ -910,6 +910,76 @@ async fn csv_query_count_one() {
assert_eq!(expected, actual);
}
+#[tokio::test]
+async fn case_when() {
+ let mut ctx = ExecutionContext::new();
+ register_aggregate_csv_by_sql(&mut ctx).await;
+ let sql = "SELECT \
+ CASE WHEN c1 = 'a' THEN 1 \
+ WHEN c1 = 'b' THEN 2 \
+ ELSE 999 END \
+ FROM aggregate_test_100 LIMIT 20";
+ let actual = execute(&mut ctx, sql).await;
+ let expected = vec![
+ vec!["999"],
+ vec!["999"],
+ vec!["2"],
+ vec!["1"],
+ vec!["2"],
+ vec!["2"],
+ vec!["999"],
+ vec!["1"],
+ vec!["999"],
+ vec!["1"],
+ vec!["999"],
+ vec!["1"],
+ vec!["999"],
+ vec!["999"],
+ vec!["2"],
+ vec!["999"],
+ vec!["999"],
+ vec!["999"],
+ vec!["999"],
+ vec!["999"],
+ ];
Review comment:
It is a bit difficult for me to confirm that this is correct. What do
you think if we just generate a table in memory with all possibilities and test
against that? IMO it is a bit more explicit and also allows to verify the cases
with null values.
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