alamb commented on code in PR #10690:
URL: https://github.com/apache/datafusion/pull/10690#discussion_r1617096612
##########
datafusion/sql/tests/sql_integration.rs:
##########
@@ -4631,6 +4631,8 @@ fn roundtrip_statement() -> Result<()> {
"select (id-1)/2, count(*) / (sum(id/10)-1) as agg_expr from
(select (id-1) as id from person) group by id",
"select CAST(id/2 as VARCHAR) NOT LIKE 'foo*' from person where
NOT EXISTS (select ta.j1_id, tb.j2_string from j1 ta join j2 tb on (ta.j1_id =
tb.j2_id))",
r#"select "First Name" from person_quoted_cols"#,
+ "select DISTINCT id FROM person;",
+ "select DISTINCT on (id) id, first_name from person order by id;",
Review Comment:
Can you also please add a test like this (without an order by)?
```sql
select DISTINCT on (id) id, first_name from person;
```
##########
datafusion/sql/src/unparser/plan.rs:
##########
@@ -271,8 +273,39 @@ impl Unparser<'_> {
relation,
)
}
- LogicalPlan::Distinct(_distinct) => {
- not_impl_err!("Unsupported operator: {plan:?}")
+ LogicalPlan::Distinct(distinct) => {
+ let (select_distinct, input) = match distinct {
+ Distinct::All(input) => (ast::Distinct::Distinct,
input.as_ref()),
+ Distinct::On(on) => {
+ let exprs = on
+ .on_expr
+ .iter()
+ .map(|e| self.expr_to_sql(e))
+ .collect::<Result<Vec<_>>>()?;
+ let items = on
+ .select_expr
+ .iter()
+ .map(|e| self.select_item_to_sql(e))
+ .collect::<Result<Vec<_>>>()?;
+ match &on.sort_expr {
+ Some(sort_expr) => {
+ if let Some(query_ref) = query {
+ query_ref
+
.order_by(self.sort_to_sql(sort_expr.clone())?);
+ } else {
+ return internal_err!(
+ "Sort operator only valid in a statement
context."
+ );
Review Comment:
I think it is to support the postgres style `DISTINCT ON`, which may not
have all the columns of the select list
Perhaps @gruuya knows more
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