xanderbailey commented on code in PR #17299:
URL: https://github.com/apache/datafusion/pull/17299#discussion_r2329524658


##########
datafusion/substrait/src/logical_plan/consumer/rel/project_rel.rs:
##########
@@ -62,7 +62,17 @@ pub async fn from_project_rel(
                 // to transform it into a column reference
                 window_exprs.insert(e.clone());
             }
-            explicit_exprs.push(name_tracker.get_uniquely_named_expr(e)?);
+            // Since substrait removes aliases, we need to assign literals 
with a UUID alias to avoid
+            // ambiguous names when the same literal is used before and after 
a join.
+            // The name tracker will ensure that two literals in the same 
project would have
+            // unique names but, it does not ensure that if a literal column 
exists in a previous
+            // project say before a join that it is deduplicated with respect 
to those columns.

Review Comment:
   I've updated some of the comments made by @vbarua. I'm happy to merge as is 
to unblock us and then I can have a go at improving the name tracker in a 
follow-up?



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