[GitHub] [arrow-rs] tustvold commented on a change in pull request #1469: Implement ArrayEqual for UnionArray

[GitBox <gi...@apache.org>]

tustvold commented on a change in pull request #1469:
URL: https://github.com/apache/arrow-rs/pull/1469#discussion_r834430189



##########
File path: arrow/src/array/equal/union.rs
##########
@@ -0,0 +1,171 @@
+// 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 crate::datatypes::Field;
+use crate::{
+    array::ArrayData, buffer::Buffer, datatypes::DataType, datatypes::UnionMode,
+};
+
+use super::{
+    equal_range, equal_values, utils::child_logical_null_buffer, utils::equal_nulls,
+};
+
+// Checks if corresponding slots in two UnionArrays are same data types
+fn equal_types(
+    lhs_fields: &[Field],
+    rhs_fields: &[Field],
+    lhs_type_ids: &[i8],
+    rhs_type_ids: &[i8],
+) -> bool {
+    let lhs_slots_types = lhs_type_ids
+        .iter()
+        .map(|type_id| lhs_fields.get(*type_id as usize).unwrap().data_type());
+
+    let rhs_slots_types = rhs_type_ids
+        .iter()
+        .map(|type_id| rhs_fields.get(*type_id as usize).unwrap().data_type());
+
+    lhs_slots_types.zip(rhs_slots_types).all(|(l, r)| l == r)
+}
+
+fn equal_dense(

Review comment:
       Much like equal_sparse below, by the time we are calling this method we have already established equality of the type_ids, I therefore wonder if we can simply compute equality of the offsets arrays, followed by computing equality of the underlying child arrays.
   
   This appears to be similar to what is done for list_equal :thinking: 

##########
File path: arrow/src/array/equal/utils.rs
##########
@@ -161,8 +168,35 @@ pub(super) fn child_logical_null_buffer(
             });
             Some(buffer.into())
         }
-        DataType::Union(_, _) => {
-            unimplemented!("Logical equality not yet implemented for union arrays")
+        DataType::Union(_, mode) => {
+            match mode {
+                UnionMode::Sparse => {
+                    // See the logic of `DataType::Struct` in `child_logical_null_buffer`.

Review comment:
       Perhaps this could be broken out into a function? I also wonder if it might be possible to implement more efficiently by truncating the longer buffer :thinking: 

##########
File path: arrow/src/array/equal/union.rs
##########
@@ -0,0 +1,171 @@
+// 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 crate::datatypes::Field;
+use crate::{
+    array::ArrayData, buffer::Buffer, datatypes::DataType, datatypes::UnionMode,
+};
+
+use super::{
+    equal_range, equal_values, utils::child_logical_null_buffer, utils::equal_nulls,
+};
+
+// Checks if corresponding slots in two UnionArrays are same data types
+fn equal_types(

Review comment:
       In order to be equal the two arrays must have the same schema and therefore `lhs_fields == rhs_fields` I think therefore this could simply just compare the type_id arrays for equality directly?




-- 
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.

To unsubscribe, e-mail: github-unsubscribe@arrow.apache.org

For queries about this service, please contact Infrastructure at:
users@infra.apache.org