alamb commented on code in PR #4753:
URL: https://github.com/apache/arrow-datafusion/pull/4753#discussion_r1058590886
##########
datafusion/core/tests/sql/union.rs:
##########
@@ -80,6 +80,23 @@ async fn union_all_with_aggregate() -> Result<()> {
Ok(())
}
+#[tokio::test]
+async fn union_all_with_count() -> Result<()> {
+ let ctx = SessionContext::new();
+ execute_to_batches(&ctx, "CREATE table t as SELECT 1 as a").await;
+ let sql = "SELECT COUNT(*) FROM (SELECT a from t UNION ALL SELECT a from
t)";
Review Comment:
👍 agrees with postgres:
```sql
postgres=# CREATE table t as SELECT 1 as a;
SELECT 1
postgres=# SELECT COUNT(*) FROM (SELECT a from t UNION ALL SELECT a from t);
ERROR: subquery in FROM must have an alias
LINE 1: SELECT COUNT(*) FROM (SELECT a from t UNION ALL SELECT a fro...
^
HINT: For example, FROM (SELECT ...) [AS] foo.
postgres=# SELECT COUNT(*) FROM (SELECT a from t UNION ALL SELECT a from t)
as sq;
count
-------
2
(1 row)
```
##########
datafusion/core/src/physical_plan/planner.rs:
##########
@@ -773,12 +773,19 @@ impl DefaultPhysicalPlanner {
)?;
Ok(Arc::new(FilterExec::try_new(runtime_expr,
physical_input)?))
}
- LogicalPlan::Union(Union { inputs, .. }) => {
+ LogicalPlan::Union(Union { inputs, schema }) => {
let physical_plans = futures::stream::iter(inputs)
.then(|lp| self.create_initial_plan(lp, session_state))
.try_collect::<Vec<_>>()
.await?;
- Ok(Arc::new(UnionExec::new(physical_plans)))
+ if schema.fields().len() <
physical_plans[0].schema().fields().len() {
Review Comment:
I wonder what is the reason to not always run
`UnionExec::try_new_with_schema`?
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