kosiew commented on code in PR #16696:
URL: https://github.com/apache/datafusion/pull/16696#discussion_r2241482599
##########
datafusion/optimizer/src/optimize_projections/mod.rs:
##########
@@ -826,6 +840,34 @@ pub fn is_projection_unnecessary(
))
}
+fn plan_contains_subquery_alias(plan: &LogicalPlan) -> bool {
+ // ambiguity of aliases can arise if there are
Review Comment:
This initial change in this PR
```rust
LogicalPlan::RecursiveQuery(_) => {
plan.inputs()
.into_iter()
.map(|input| {
indices
.clone()
.with_projection_beneficial()
.with_plan_exprs(&plan, input.schema())
})
.collect::<Result<Vec<_>>>()?
}
```
in fn optimize_projectsion caused this slt test to fail
```
External error: 1 errors in file
/Users/kosiew/GitHub/datafusion/datafusion/sqllogictest/test_files/cte.slt
1. query failed: DataFusion error: Optimizer rule 'optimize_projections'
failed
caused by
Schema error: No field named __scalar_sq_1.prices_row_num. Did you mean
'__scalar_sq_3.prices_row_num'?.
[SQL] WITH RECURSIVE "recursive_cte" AS (
...
```
```sql
# CTE within window function inside nested CTE works. This test demonstrates
using a nested window function to recursively iterate over a column.
query RRII
WITH RECURSIVE "recursive_cte" AS (
(
WITH "min_prices_row_num_cte" AS (
...
```
After a lot of investigation, I found that it failed because the recursive
cte has several subquery aliases.
Instead of tweaking subquery aliases for recursive queries, I added a
bypass for recursive ctes with 2 or more subquery aliases.
```rust
LogicalPlan::RecursiveQuery(_) => {
if plan_contains_subquery_alias(&plan) {
//
https://github.com/apache/datafusion/pull/16696#discussion_r2241482599
return Ok(Transformed::no(plan));
}
...
```
which enabled the slt test to pass.
I thought this was an improvement because before this change, recursive
queries were not transformed by optimize_projections at all.
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