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Add union_tag
scalar function
#14687
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8d07d08
feat: add union_tag scalar function
gstvg 1e3675b
Merge remote-tracking branch 'apache/main' into union_tag
alamb 288a3c1
Merge remote-tracking branch 'apache/main' into union_tag
alamb 47e785a
update for new api
alamb 680e7fa
Add test for second field type
alamb 8d9dda0
Merge remote-tracking branch 'apache/main' into union_tag
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Original file line number | Diff line number | Diff line change |
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@@ -0,0 +1,225 @@ | ||
// Licensed to the Apache Software Foundation (ASF) under one | ||
// or more contributor license agreements. See the NOTICE file | ||
// distributed with this work for additional information | ||
// regarding copyright ownership. The ASF licenses this file | ||
// to you under the Apache License, Version 2.0 (the | ||
// "License"); you may not use this file except in compliance | ||
// with the License. You may obtain a copy of the License at | ||
// | ||
// http://www.apache.org/licenses/LICENSE-2.0 | ||
// | ||
// Unless required by applicable law or agreed to in writing, | ||
// software distributed under the License is distributed on an | ||
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY | ||
// KIND, either express or implied. See the License for the | ||
// specific language governing permissions and limitations | ||
// under the License. | ||
|
||
use arrow::array::{Array, AsArray, DictionaryArray, Int8Array, StringArray}; | ||
use arrow::datatypes::DataType; | ||
use datafusion_common::utils::take_function_args; | ||
use datafusion_common::{exec_datafusion_err, exec_err, Result, ScalarValue}; | ||
use datafusion_doc::Documentation; | ||
use datafusion_expr::{ColumnarValue, ScalarFunctionArgs}; | ||
use datafusion_expr::{ScalarUDFImpl, Signature, Volatility}; | ||
use datafusion_macros::user_doc; | ||
use std::sync::Arc; | ||
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||
#[user_doc( | ||
doc_section(label = "Union Functions"), | ||
description = "Returns the name of the currently selected field in the union", | ||
syntax_example = "union_tag(union_expression)", | ||
sql_example = r#"```sql | ||
❯ select union_column, union_tag(union_column) from table_with_union; | ||
+--------------+-------------------------+ | ||
| union_column | union_tag(union_column) | | ||
+--------------+-------------------------+ | ||
| {a=1} | a | | ||
| {b=3.0} | b | | ||
| {a=4} | a | | ||
| {b=} | b | | ||
| {a=} | a | | ||
+--------------+-------------------------+ | ||
```"#, | ||
standard_argument(name = "union", prefix = "Union") | ||
)] | ||
#[derive(Debug)] | ||
pub struct UnionTagFunc { | ||
signature: Signature, | ||
} | ||
|
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impl Default for UnionTagFunc { | ||
fn default() -> Self { | ||
Self::new() | ||
} | ||
} | ||
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impl UnionTagFunc { | ||
pub fn new() -> Self { | ||
Self { | ||
signature: Signature::any(1, Volatility::Immutable), | ||
} | ||
} | ||
} | ||
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impl ScalarUDFImpl for UnionTagFunc { | ||
fn as_any(&self) -> &dyn std::any::Any { | ||
self | ||
} | ||
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fn name(&self) -> &str { | ||
"union_tag" | ||
} | ||
|
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fn signature(&self) -> &Signature { | ||
&self.signature | ||
} | ||
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fn return_type(&self, _: &[DataType]) -> Result<DataType> { | ||
Ok(DataType::Dictionary( | ||
Box::new(DataType::Int8), | ||
Box::new(DataType::Utf8), | ||
)) | ||
} | ||
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fn invoke_with_args(&self, args: ScalarFunctionArgs) -> Result<ColumnarValue> { | ||
let [union_] = take_function_args("union_tag", args.args)?; | ||
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match union_ { | ||
ColumnarValue::Array(array) | ||
if matches!(array.data_type(), DataType::Union(_, _)) => | ||
{ | ||
let union_array = array.as_union(); | ||
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let keys = Int8Array::try_new(union_array.type_ids().clone(), None)?; | ||
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let fields = match union_array.data_type() { | ||
DataType::Union(fields, _) => fields, | ||
_ => unreachable!(), | ||
}; | ||
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// Union fields type IDs only constraints are being unique and in the 0..128 range: | ||
// They may not start at 0, be sequential, or even contiguous. | ||
// Therefore, we allocate a values vector with a length equal to the highest type ID plus one, | ||
// ensuring that each field's name can be placed at the index corresponding to its type ID. | ||
let values_len = fields | ||
.iter() | ||
.map(|(type_id, _)| type_id + 1) | ||
.max() | ||
.unwrap_or_default() as usize; | ||
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let mut values = vec![""; values_len]; | ||
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for (type_id, field) in fields.iter() { | ||
values[type_id as usize] = field.name().as_str() | ||
} | ||
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let values = Arc::new(StringArray::from(values)); | ||
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// SAFETY: union type_ids are validated to not be smaller than zero. | ||
// values len is the union biggest type id plus one. | ||
// keys is built from the union type_ids, which contains only valid type ids | ||
// therefore, `keys[i] >= values.len() || keys[i] < 0` never occurs | ||
let dict = unsafe { DictionaryArray::new_unchecked(keys, values) }; | ||
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Ok(ColumnarValue::Array(Arc::new(dict))) | ||
} | ||
ColumnarValue::Scalar(ScalarValue::Union(value, fields, _)) => match value { | ||
Some((value_type_id, _)) => fields | ||
.iter() | ||
.find(|(type_id, _)| value_type_id == *type_id) | ||
.map(|(_, field)| { | ||
ColumnarValue::Scalar(ScalarValue::Dictionary( | ||
Box::new(DataType::Int8), | ||
Box::new(field.name().as_str().into()), | ||
)) | ||
}) | ||
.ok_or_else(|| { | ||
exec_datafusion_err!( | ||
"union_tag: union scalar with unknow type_id {value_type_id}" | ||
) | ||
}), | ||
None => Ok(ColumnarValue::Scalar(ScalarValue::try_new_null( | ||
args.return_field.data_type(), | ||
)?)), | ||
}, | ||
v => exec_err!("union_tag only support unions, got {:?}", v.data_type()), | ||
} | ||
} | ||
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fn documentation(&self) -> Option<&Documentation> { | ||
self.doc() | ||
} | ||
} | ||
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#[cfg(test)] | ||
mod tests { | ||
use super::UnionTagFunc; | ||
use arrow::datatypes::{DataType, Field, UnionFields, UnionMode}; | ||
use datafusion_common::ScalarValue; | ||
use datafusion_expr::{ColumnarValue, ScalarFunctionArgs, ScalarUDFImpl}; | ||
use std::sync::Arc; | ||
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// when it becomes possible to construct union scalars in SQL, this should go to sqllogictests | ||
#[test] | ||
fn union_scalar() { | ||
let fields = [(0, Arc::new(Field::new("a", DataType::UInt32, false)))] | ||
.into_iter() | ||
.collect(); | ||
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let scalar = ScalarValue::Union( | ||
Some((0, Box::new(ScalarValue::UInt32(Some(0))))), | ||
fields, | ||
UnionMode::Dense, | ||
); | ||
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let return_type = | ||
DataType::Dictionary(Box::new(DataType::Int8), Box::new(DataType::Utf8)); | ||
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let result = UnionTagFunc::new() | ||
.invoke_with_args(ScalarFunctionArgs { | ||
args: vec![ColumnarValue::Scalar(scalar)], | ||
number_rows: 1, | ||
return_field: &Field::new("res", return_type, true), | ||
arg_fields: vec![], | ||
}) | ||
.unwrap(); | ||
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assert_scalar( | ||
result, | ||
ScalarValue::Dictionary(Box::new(DataType::Int8), Box::new("a".into())), | ||
); | ||
} | ||
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#[test] | ||
fn union_scalar_empty() { | ||
let scalar = ScalarValue::Union(None, UnionFields::empty(), UnionMode::Dense); | ||
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let return_type = | ||
DataType::Dictionary(Box::new(DataType::Int8), Box::new(DataType::Utf8)); | ||
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let result = UnionTagFunc::new() | ||
.invoke_with_args(ScalarFunctionArgs { | ||
args: vec![ColumnarValue::Scalar(scalar)], | ||
number_rows: 1, | ||
return_field: &Field::new("res", return_type, true), | ||
arg_fields: vec![], | ||
}) | ||
.unwrap(); | ||
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assert_scalar( | ||
result, | ||
ScalarValue::Dictionary( | ||
Box::new(DataType::Int8), | ||
Box::new(ScalarValue::Utf8(None)), | ||
), | ||
); | ||
} | ||
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fn assert_scalar(value: ColumnarValue, expected: ScalarValue) { | ||
match value { | ||
ColumnarValue::Array(array) => panic!("expected scalar got {array:?}"), | ||
ColumnarValue::Scalar(scalar) => assert_eq!(scalar, expected), | ||
} | ||
} | ||
} |
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Original file line number | Diff line number | Diff line change |
---|---|---|
|
@@ -15,6 +15,9 @@ | |
# specific language governing permissions and limitations | ||
# under the License. | ||
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# Note: union_table is registered via Rust code in the sqllogictest test harness | ||
# because there is no way to create a union type in SQL today | ||
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########## | ||
## UNION DataType Tests | ||
########## | ||
|
@@ -23,7 +26,8 @@ query ?I | |
select union_column, union_extract(union_column, 'int') from union_table; | ||
---- | ||
{int=1} 1 | ||
{int=2} 2 | ||
{string=bar} NULL | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. I added a new row to the table so we could test union_tag with a field that did not exist, per @Omega359 's suggestion |
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{int=3} 3 | ||
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query error DataFusion error: Execution error: field bool not found on union | ||
select union_extract(union_column, 'bool') from union_table; | ||
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@@ -45,3 +49,19 @@ select union_extract(union_column, 1) from union_table; | |
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query error DataFusion error: Error during planning: The function 'union_extract' expected 2 arguments but received 3 | ||
select union_extract(union_column, 'a', 'b') from union_table; | ||
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query ?T | ||
select union_column, union_tag(union_column) from union_table; | ||
---- | ||
{int=1} int | ||
{string=bar} string | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. I added a new test as suggested |
||
{int=3} int | ||
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query error DataFusion error: Error during planning: 'union_tag' does not support zero arguments | ||
select union_tag() from union_table; | ||
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query error DataFusion error: Error during planning: The function 'union_tag' expected 1 arguments but received 2 | ||
select union_tag(union_column, 'int') from union_table; | ||
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query error DataFusion error: Execution error: union_tag only support unions, got Utf8 | ||
select union_tag('int') from union_table; |
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The union column used on the sqllogictests contains a single field with type id 3, so this is put to the test
datafusion/datafusion/sqllogictest/src/test_context.rs
Lines 411 to 430 in e4b78c7
datafusion/datafusion/sqllogictest/src/test_context.rs
Lines 117 to 120 in e4b78c7