support of null as merge function

1 files changed, 3 insertions, 1 deletions

diff --git a/ydb/library/yql/sql/v1/aggregation.cpp b/ydb/library/yql/sql/v1/aggregation.cpp
index c59f39d3dfd..64a9c657db9 100644
--- a/ydb/library/yql/sql/v1/aggregation.cpp
+++ b/ydb/library/yql/sql/v1/aggregation.cpp
@@ -1155,7 +1155,9 @@ private:
 
         Lambdas[0] = BuildLambda(Pos, Y("value", "parent"), Y("NamedApply", exprs[adjustArgsCount], Q(Y("value")), Y("AsStruct"), Y("DependsOn", "parent")));
         Lambdas[1] = BuildLambda(Pos, Y("value", "state", "parent"), Y("NamedApply", exprs[adjustArgsCount + 1], Q(Y("state", "value")), Y("AsStruct"), Y("DependsOn", "parent")));
-        Lambdas[2] = BuildLambda(Pos, Y("one", "two"), Y("Apply", exprs[adjustArgsCount + 2], "one", "two"));
+        Lambdas[2] = BuildLambda(Pos, Y("one", "two"), Y("IfType", exprs[adjustArgsCount + 2], Y("NullType"), 
+            BuildLambda(Pos, Y(), Y("Void")),
+            BuildLambda(Pos, Y(), Y("Apply", exprs[adjustArgsCount + 2], "one", "two"))));
 
         for (size_t i = 3U; i < Lambdas.size(); ++i) {
             const auto j = adjustArgsCount + i;