[GitHub] [arrow-datafusion] waynexia commented on a diff in pull request #6135: Substrait: Fix incorrect join key fields (indices) when same table is being used more than once

["waynexia (via GitHub)" <gi...@apache.org>]

waynexia commented on code in PR #6135:
URL: https://github.com/apache/arrow-datafusion/pull/6135#discussion_r1184592657


##########
datafusion/substrait/src/logical_plan/producer.rs:
##########
@@ -15,7 +15,7 @@
 // specific language governing permissions and limitations
 // under the License.
 
-use std::{collections::HashMap, sync::Arc};
+use std::{collections::HashMap, usize};

Review Comment:
   style: This type should be in the scope by default
   
   ```suggestion
   use std::collections::HashMap;
   ```



##########
datafusion/substrait/tests/roundtrip_logical_plan.rs:
##########
@@ -278,6 +278,18 @@ mod tests {
         roundtrip("SELECT a,b,c,d,e FROM datafusion.public.data;").await
     }
 
+    #[tokio::test]
+    async fn roundtrip_inner_join_table_reuse() -> Result<()> {
+        assert_expected_plan(
+            "SELECT d1.b, d2.c FROM data d1 JOIN data d2 ON d1.a = d2.a",
+            "Projection: data.b, data.c\
+            \n  Inner Join: data.a = data.a\
+            \n    TableScan: data projection=[a, b]\
+            \n    TableScan: data projection=[a, c]",

Review Comment:
   I tried this case against the main branch and it can pass. I guess this is not the original query that causes the error?
   
   BTW, if two tables have the same name, does it means they are the same table? (for this case, `d1` and `d2` are the same table `data`). If so I think we need not distinguish "different" columns because they will eventually refer to the same column. Please let me know if I missed anything



##########
datafusion/substrait/src/logical_plan/producer.rs:
##########
@@ -363,6 +344,40 @@ pub fn to_substrait_rel(
     }
 }
 
+fn to_substrait_join_expr(
+    join_conditions: &Vec<(Expr, Expr)>,
+    eq_op: Operator,
+    left_schema: &DFSchemaRef,
+    right_schema: &DFSchemaRef,
+    extension_info: &mut (
+        Vec<extensions::SimpleExtensionDeclaration>,
+        HashMap<String, u32>,
+    ),
+) -> Result<Expression> {
+    // Only support AND confunction for each binary expression in join conditions

Review Comment:
   maybe a typo?
   ```suggestion
       // Only support AND conjunction for each binary expression in join conditions
   ```



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