goldmedal commented on code in PR #21593:
URL: https://github.com/apache/datafusion/pull/21593#discussion_r3114736414
##########
datafusion/sql/src/unparser/ast.rs:
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@@ -162,9 +162,28 @@ pub struct SelectBuilder {
qualify: Option<ast::Expr>,
value_table_mode: Option<ast::ValueTableMode>,
flavor: Option<SelectFlavor>,
+ /// Counter for generating unique LATERAL FLATTEN aliases within this
SELECT.
+ flatten_alias_counter: usize,
}
impl SelectBuilder {
+ /// Generate a unique alias for a LATERAL FLATTEN relation
+ /// (`_unnest_1`, `_unnest_2`, …). Each call returns a fresh name.
+ pub fn next_flatten_alias(&mut self) -> String {
+ self.flatten_alias_counter += 1;
+ format!("_unnest_{}", self.flatten_alias_counter)
Review Comment:
@yonatan-sevenai The test case for the multiple unnest is still missing.
Could you add it? I expect something like the following to trigger the alias
counter.
```sql
SELECT * FROM j1, UNNEST(extract_array(j1_string)), j2,
UNNEST(extract_array(j2_string)) LIMIT 5
```
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