fix: Revert "Fix/support duplicate column names #6543 (#21126)" (#21254)

## Which issue does this PR close?

<!--
We generally require a GitHub issue to be filed for all bug fixes and
enhancements and this helps us generate change logs for our releases.
You can link an issue to this PR using the GitHub syntax. For example
`Closes #123` indicates that this PR will close issue #123.
-->

- Closes #21253.

## Rationale for this change

<!--
Why are you proposing this change? If this is already explained clearly
in the issue then this section is not needed.
Explaining clearly why changes are proposed helps reviewers understand
your changes and offer better suggestions for fixes.
-->

- Get extended CI tests running again.

## What changes are included in this PR?

<!--
There is no need to duplicate the description in the issue here but it
is sometimes worth providing a summary of the individual changes in this
PR.
-->

- This reverts commit aadae6b.

## Are these changes tested?

<!--
We typically require tests for all PRs in order to:
1. Prevent the code from being accidentally broken by subsequent changes
2. Serve as another way to document the expected behavior of the code

If tests are not included in your PR, please explain why (for example,
are they covered by existing tests)?
-->

Existing CI.

## Are there any user-facing changes?

<!--
If there are user-facing changes then we may require documentation to be
updated before approving the PR.
-->

No change since a released version. #21126 fixed a bug that this will
reintroduce, but we'll need to fix test files first.

<!--
If there are any breaking changes to public APIs, please add the `api
change` label.
-->

Author: mbutrovich

datafusion/sql/src/select.rs

@@ -23,9 +23,8 @@ use crate::planner::{ContextProvider, PlannerContext, SqlToRel};
 use crate::query::to_order_by_exprs_with_select;
 use crate::utils::{
     CheckColumnsMustReferenceAggregatePurpose, CheckColumnsSatisfyExprsPurpose,
-    check_columns_satisfy_exprs, deduplicate_select_expr_names, extract_aliases,
-    rebase_expr, resolve_aliases_to_exprs, resolve_columns, resolve_positions_to_exprs,
-    rewrite_recursive_unnests_bottom_up,
+    check_columns_satisfy_exprs, extract_aliases, rebase_expr, resolve_aliases_to_exprs,
+    resolve_columns, resolve_positions_to_exprs, rewrite_recursive_unnests_bottom_up,
 };
 
 use datafusion_common::error::DataFusionErrorBuilder;
@@ -110,10 +109,6 @@ impl<S: ContextProvider> SqlToRel<'_, S> {
             planner_context,
         )?;
 
-        // Auto-suffix duplicate expression names (e.g. cov, cov → cov, cov:1)
-        // before projection so that the unique-name constraint is satisfied.
-        let select_exprs = deduplicate_select_expr_names(select_exprs);
-
         // Having and group by clause may reference aliases defined in select projection
         let projected_plan = self.project(base_plan.clone(), select_exprs)?;
         let select_exprs = projected_plan.expressions();

datafusion/sql/src/utils.rs

@@ -33,7 +33,6 @@ use datafusion_expr::builder::get_struct_unnested_columns;
 use datafusion_expr::expr::{
     Alias, GroupingSet, Unnest, WindowFunction, WindowFunctionParams,
 };
-use datafusion_expr::select_expr::SelectExpr;
 use datafusion_expr::utils::{expr_as_column_expr, find_column_exprs};
 use datafusion_expr::{
     ColumnUnnestList, Expr, ExprSchemable, LogicalPlan, col, expr_vec_fmt,
@@ -634,38 +633,6 @@ fn push_projection_dedupl(projection: &mut Vec<Expr>, expr: Expr) {
         projection.push(expr);
     }
 }
-
-/// Auto-suffix duplicate SELECT expression names with `:{count}`.
-///
-/// The first occurrence keeps its original name so that ORDER BY / HAVING
-/// references resolve correctly. Wildcards are left untouched because they
-/// are expanded later in `project_with_validation`.
-///
-/// Duplicates are detected by the schema name of each expression, which
-/// identifies logically identical expressions before column normalization.
-pub(crate) fn deduplicate_select_expr_names(exprs: Vec<SelectExpr>) -> Vec<SelectExpr> {
-    let mut seen: HashMap<String, usize> = HashMap::new();
-    exprs
-        .into_iter()
-        .map(|select_expr| match select_expr {
-            SelectExpr::Expression(expr) => {
-                let name = expr.schema_name().to_string();
-                let count = seen.entry(name.clone()).or_insert(0);
-                let result = if *count > 0 {
-                    let (_qualifier, field_name) = expr.qualified_name();
-                    SelectExpr::Expression(expr.alias(format!("{field_name}:{count}")))
-                } else {
-                    SelectExpr::Expression(expr)
-                };
-                *count += 1;
-                result
-            }
-            // Leave wildcards alone — they are expanded later
-            other => other,
-        })
-        .collect()
-}
-
 /// The context is we want to rewrite unnest() into InnerProjection->Unnest->OuterProjection
 /// Given an expression which contains unnest expr as one of its children,
 /// Try transform depends on unnest type

datafusion/sql/tests/sql_integration.rs

@@ -789,13 +789,11 @@ fn select_column_does_not_exist() {
 #[test]
 fn select_repeated_column() {
     let sql = "SELECT age, age FROM person";
-    let plan = logical_plan(sql).unwrap();
+    let err = logical_plan(sql).expect_err("query should have failed");
+
     assert_snapshot!(
-        plan,
-        @r"
-    Projection: person.age, person.age AS age:1
-      TableScan: person
-    "
+        err.strip_backtrace(),
+        @r#"Error during planning: Projections require unique expression names but the expression "person.age" at position 0 and "person.age" at position 1 have the same name. Consider aliasing ("AS") one of them."#
     );
 }
 
@@ -1533,14 +1531,11 @@ fn select_simple_aggregate_column_does_not_exist() {
 #[test]
 fn select_simple_aggregate_repeated_aggregate() {
     let sql = "SELECT MIN(age), MIN(age) FROM person";
-    let plan = logical_plan(sql).unwrap();
+    let err = logical_plan(sql).expect_err("query should have failed");
+
     assert_snapshot!(
-        plan,
-        @r"
-    Projection: min(person.age), min(person.age) AS min(person.age):1
-      Aggregate: groupBy=[[]], aggr=[[min(person.age)]]
-        TableScan: person
-    "
+        err.strip_backtrace(),
+        @r#"Error during planning: Projections require unique expression names but the expression "min(person.age)" at position 0 and "min(person.age)" at position 1 have the same name. Consider aliasing ("AS") one of them."#
     );
 }
 
@@ -1589,14 +1584,11 @@ fn select_from_typed_string_values() {
 #[test]
 fn select_simple_aggregate_repeated_aggregate_with_repeated_aliases() {
     let sql = "SELECT MIN(age) AS a, MIN(age) AS a FROM person";
-    let plan = logical_plan(sql).unwrap();
+    let err = logical_plan(sql).expect_err("query should have failed");
+
     assert_snapshot!(
-        plan,
-        @r"
-    Projection: min(person.age) AS a, min(person.age) AS a AS a:1
-      Aggregate: groupBy=[[]], aggr=[[min(person.age)]]
-        TableScan: person
-    "
+        err.strip_backtrace(),
+        @r#"Error during planning: Projections require unique expression names but the expression "min(person.age) AS a" at position 0 and "min(person.age) AS a" at position 1 have the same name. Consider aliasing ("AS") one of them."#
     );
 }
 
@@ -1633,14 +1625,11 @@ fn select_simple_aggregate_with_groupby_with_aliases() {
 #[test]
 fn select_simple_aggregate_with_groupby_with_aliases_repeated() {
     let sql = "SELECT state AS a, MIN(age) AS a FROM person GROUP BY state";
-    let plan = logical_plan(sql).unwrap();
+    let err = logical_plan(sql).expect_err("query should have failed");
+
     assert_snapshot!(
-        plan,
-        @r"
-    Projection: person.state AS a, min(person.age) AS a AS a:1
-      Aggregate: groupBy=[[person.state]], aggr=[[min(person.age)]]
-        TableScan: person
-    "
+        err.strip_backtrace(),
+        @r#"Error during planning: Projections require unique expression names but the expression "person.state AS a" at position 0 and "min(person.age) AS a" at position 1 have the same name. Consider aliasing ("AS") one of them."#
     );
 }
 
@@ -1761,14 +1750,11 @@ fn select_simple_aggregate_with_groupby_can_use_alias() {
 #[test]
 fn select_simple_aggregate_with_groupby_aggregate_repeated() {
     let sql = "SELECT state, MIN(age), MIN(age) FROM person GROUP BY state";
-    let plan = logical_plan(sql).unwrap();
+    let err = logical_plan(sql).expect_err("query should have failed");
+
     assert_snapshot!(
-        plan,
-        @r"
-    Projection: person.state, min(person.age), min(person.age) AS min(person.age):1
-      Aggregate: groupBy=[[person.state]], aggr=[[min(person.age)]]
-        TableScan: person
-    "
+        err.strip_backtrace(),
+        @r#"Error during planning: Projections require unique expression names but the expression "min(person.age)" at position 1 and "min(person.age)" at position 2 have the same name. Consider aliasing ("AS") one of them."#
     );
 }
 

datafusion/sqllogictest/test_files/aggregate.slt

@@ -7941,16 +7941,21 @@ select count(), count() * count() from t;
 ----
 2 4
 
-# Duplicate aggregate expressions are now auto-suffixed
-query II
+# DataFusion error: Error during planning: Projections require unique expression names but the expression "count\(Int64\(1\)\)" at position 0 and "count\(Int64\(1\)\)" at position 1 have the same name\. Consider aliasing \("AS"\) one of them\.
+query error
 select count(1), count(1) from t;
-----
-2 2
 
-query II
+# DataFusion error: Error during planning: Projections require unique expression names but the expression "count\(Int64\(1\)\)" at position 0 and "count\(Int64\(1\)\)" at position 1 have the same name\. Consider aliasing \("AS"\) one of them\.
+query error
+explain select count(1), count(1) from t;
+
+# DataFusion error: Error during planning: Projections require unique expression names but the expression "count\(Int64\(1\) AS \)" at position 0 and "count\(Int64\(1\) AS \)" at position 1 have the same name\. Consider aliasing \("AS"\) one of them\.
+query error
 select count(), count() from t;
-----
-2 2
+
+# DataFusion error: Error during planning: Projections require unique expression names but the expression "count\(Int64\(1\) AS \)" at position 0 and "count\(Int64\(1\) AS \)" at position 1 have the same name\. Consider aliasing \("AS"\) one of them\.
+query error
+explain select count(), count() from t;
 
 query II
 select count(1), count(2) from t;

datafusion/sqllogictest/test_files/duplicate_column_alias.slt

@@ -547,16 +547,8 @@ select unnest(column1) from (select * from (values([1,2,3]), ([4,5,6])) limit 1
 5
 6
 
-query II
+query error DataFusion error: Error during planning: Projections require unique expression names but the expression "UNNEST\(unnest_table.column1\)" at position 0 and "UNNEST\(unnest_table.column1\)" at position 1 have the same name. Consider aliasing \("AS"\) one of them.
 select unnest(column1), unnest(column1) from unnest_table;
-----
-1 1
-2 2
-3 3
-4 4
-5 5
-6 6
-12 12
 
 query II
 select unnest(column1), unnest(column1) u1 from unnest_table;