[KQP RBO] Add union all (#26359)

Author: denis0x0D

ydb/core/kqp/expr_nodes/kqp_expr_nodes.json

@@ -843,6 +843,15 @@
                 {"Index": 3, "Name": "JoinKeys", "Type": "TDqJoinKeyTupleList"}
             ]
         },
+        {
+            "Name": "TKqpOpUnionAll",
+            "Base": "TCallable",
+            "Match": {"Type": "Callable", "Name": "KqpOpUnionAll"},
+            "Children": [
+                {"Index": 0, "Name": "LeftInput", "Type": "TExprBase"},
+                {"Index": 1, "Name": "RightInput", "Type": "TExprBase"}
+            ]
+        },
         {
             "Name": "TKqpOpLimit",
             "Base": "TCallable",

ydb/core/kqp/opt/kqp_type_ann.cpp

@@ -2380,6 +2380,14 @@ TStatus AnnotateOpJoin(const TExprNode::TPtr& input, TExprContext& ctx) {
     return TStatus::Ok;
 }
 
+TStatus AnnotateOpUnionAll(const TExprNode::TPtr& input, TExprContext& ctx) {
+    Y_UNUSED(ctx);
+    auto leftInputType = input->ChildPtr(TKqpOpJoin::idx_LeftInput)->GetTypeAnn();
+    // TODO: Add sanity checks.
+    input->SetTypeAnn(leftInputType);
+    return TStatus::Ok;
+}
+
 TStatus AnnotateOpLimit(const TExprNode::TPtr& input, TExprContext& ctx) {
     Y_UNUSED(ctx);
     const TTypeAnnotationNode* inputType = input->ChildPtr(TKqpOpRoot::idx_Input)->GetTypeAnn();
@@ -2608,6 +2616,10 @@ TAutoPtr<IGraphTransformer> CreateKqpTypeAnnotationTransformer(const TString& cl
                 return AnnotateOpJoin(input, ctx);
             }
 
+            if (TKqpOpUnionAll::Match(input.Get())) {
+                return AnnotateOpUnionAll(input, ctx);
+            }
+
             if (TKqpOpLimit::Match(input.Get())) {
                 return AnnotateOpLimit(input, ctx);
             }