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feat : Display function alias in output column name #17690

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Merged
merged 5 commits into from
Sep 25, 2025
Merged

feat : Display function alias in output column name #17690

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2b7f22d
display function's alias name in output column
devampatel03 Sep 20, 2025
404411f
Update function.rs
devampatel03 Sep 20, 2025
0fedb3b
Merge branch 'main' into devampatel03/17469/enhancement/show-function…
devampatel03 Sep 21, 2025
13f4112
updated verbose name format
devampatel03 Sep 23, 2025
1c51eab
simplify alias logic and removing args clone
devampatel03 Sep 24, 2025
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16 changes: 8 additions & 8 deletions datafusion-examples/examples/date_time_functions.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -492,14 +492,14 @@ async fn query_to_char() -> Result<()> {

assert_batches_eq!(
&[
"+------------------------------+",
"| to_char(t.values,t.patterns) |",
"+------------------------------+",
"| 2020-09-01 |",
"| 2020:09:02 |",
"| 20200903 |",
"| 04-09-2020 |",
"+------------------------------+",
"+----------------------------------+",
"| date_format(t.values,t.patterns) |",
"+----------------------------------+",
"| 2020-09-01 |",
"| 2020:09:02 |",
"| 20200903 |",
"| 04-09-2020 |",
"+----------------------------------+",
],
&result
);
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14 changes: 7 additions & 7 deletions datafusion/core/tests/user_defined/user_defined_aggregates.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -379,13 +379,13 @@ async fn test_user_defined_functions_with_alias() -> Result<()> {

let alias_result = plan_and_collect(&ctx, "SELECT dummy_alias(i) FROM t").await?;

insta::assert_snapshot!(batches_to_string(&alias_result), @r###"
+------------+
| dummy(t.i) |
+------------+
| 1.0 |
+------------+
"###);
insta::assert_snapshot!(batches_to_string(&alias_result), @r"
+------------------+
| dummy_alias(t.i) |
+------------------+
| 1.0 |
+------------------+
");

Ok(())
}
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14 changes: 7 additions & 7 deletions datafusion/core/tests/user_defined/user_defined_scalar_functions.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -478,13 +478,13 @@ async fn test_user_defined_functions_with_alias() -> Result<()> {
"###);

let alias_result = plan_and_collect(&ctx, "SELECT dummy_alias(i) FROM t").await?;
insta::assert_snapshot!(batches_to_string(&alias_result), @r###"
+------------+
| dummy(t.i) |
+------------+
| 1 |
+------------+
"###);
insta::assert_snapshot!(batches_to_string(&alias_result), @r"
+------------------+
| dummy_alias(t.i) |
+------------------+
| 1 |
+------------------+
");

Ok(())
}
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41 changes: 38 additions & 3 deletions datafusion/sql/src/expr/function.rs
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@waynexia waynexia Sep 25, 2025

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should we do the same for WindowFunction?

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@alamb alamb Sep 25, 2025

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Yes I think so -- I added a note to the ticket

Original file line number Diff line number Diff line change
Expand Up @@ -270,7 +270,24 @@ impl<S: ContextProvider> SqlToRel<'_, S> {
// User-defined function (UDF) should have precedence
if let Some(fm) = self.context_provider.get_function_meta(&name) {
let args = self.function_args_to_expr(args, schema, planner_context)?;
return Ok(Expr::ScalarFunction(ScalarFunction::new_udf(fm, args)));
let inner = ScalarFunction::new_udf(fm, args);

if name.eq_ignore_ascii_case(inner.name()) {
return Ok(Expr::ScalarFunction(inner));
} else {
// If the function is called by an alias, a verbose string representation is created
// (e.g., "my_alias(arg1, arg2)") and the expression is wrapped in an `Alias`
// to ensure the output column name matches the user's query.
let arg_names = inner
.args
.iter()
.map(|arg| arg.to_string())
.collect::<Vec<_>>()
.join(",");
let verbose_alias = format!("{name}({arg_names})");

return Ok(Expr::ScalarFunction(inner).alias(verbose_alias));
}
}

// Build Unnest expression
Expand Down Expand Up @@ -472,14 +489,32 @@ impl<S: ContextProvider> SqlToRel<'_, S> {
null_treatment,
} = aggregate_expr;

return Ok(Expr::AggregateFunction(expr::AggregateFunction::new_udf(
let inner = expr::AggregateFunction::new_udf(
func,
args,
distinct,
filter,
order_by,
null_treatment,
)));
);

if name.eq_ignore_ascii_case(inner.func.name()) {
return Ok(Expr::AggregateFunction(inner));
} else {
// If the function is called by an alias, a verbose string representation is created
// (e.g., "my_alias(arg1, arg2)") and the expression is wrapped in an `Alias`
// to ensure the output column name matches the user's query.
let arg_names = inner
.params
.args
.iter()
.map(|arg| arg.to_string())
.collect::<Vec<_>>()
.join(",");
let verbose_alias = format!("{name}({arg_names})");

return Ok(Expr::AggregateFunction(inner).alias(verbose_alias));
}
}
}

Expand Down