[yql] Don't fuse FlatMap with outer dependencies with inner grouping op (#5767)

Author: rvu1024

ydb/library/yql/core/common_opt/yql_co_flow1.cpp

@@ -1404,12 +1404,14 @@ TExprNode::TPtr OptimizeFlatMap(const TExprNode::TPtr& node, TExprContext& ctx,
         }
     }
 
-    if (node->Head().IsCallable({"GroupByKey", "CombineByKey"})) {
-        return FuseFlatMapOverByKey<false>(*node, ctx);
-    }
+    if (self.Lambda().Ref().IsComplete()) {
+        if (node->Head().IsCallable({"GroupByKey", "CombineByKey"})) {
+            return FuseFlatMapOverByKey<false>(*node, ctx);
+        }
 
-    if (node->Head().IsCallable({"PartitionByKey", "PartitionsByKeys"})) {
-        return FuseFlatMapOverByKey<true>(*node, ctx);
+        if (node->Head().IsCallable({"PartitionByKey", "PartitionsByKeys"})) {
+            return FuseFlatMapOverByKey<true>(*node, ctx);
+        }
     }
 
     if (node->Head().IsCallable("ForwardList")) {

ydb/library/yql/tests/s-expressions/yt_native_file/part2/canondata/result.json

@@ -462,9 +462,9 @@
     ],
     "test.test[Builtins-CombineByKey-Debug]": [
         {
-            "checksum": "e730db3e33eab6087d81bf025ad77153",
-            "size": 1609,
-            "uri": "https://{canondata_backend}/1925842/10082a9422a4aa36d413e7a0729f64ea52764084/resource.tar.gz#test.test_Builtins-CombineByKey-Debug_/opt.yql"
+            "checksum": "1e7fb9d33dfbb7f4f52493ce77bfde0e",
+            "size": 1687,
+            "uri": "https://{canondata_backend}/1784117/190d0b39c848aa0cee8a7d16e5c054f8e0c367a6/resource.tar.gz#test.test_Builtins-CombineByKey-Debug_/opt.yql"
         },
         {
             "checksum": "99a23a80241cdd0057583910f9155f61",