fix 0 columns in result scheme

2 files changed, 33 insertions, 0 deletions

diff --git a/ydb/core/fq/libs/result_formatter/result_formatter.cpp b/ydb/core/fq/libs/result_formatter/result_formatter.cpp
index 8941dcb8860..18b6165f3c1 100644
--- a/ydb/core/fq/libs/result_formatter/result_formatter.cpp
+++ b/ydb/core/fq/libs/result_formatter/result_formatter.cpp
@@ -405,6 +405,7 @@ void FormatResultSet(NJson::TJsonValue& root, const NYdb::TResultSet& resultSet,
     THolderFactory holderFactory(alloc.Ref(), memInfo);
 
     NJson::TJsonValue& columns = root["columns"];
+    columns.SetType(NJson::JSON_ARRAY);
     const auto& columnsMeta = resultSet.GetColumnsMeta();
 
     TVector<TTypePair> columnTypes;
diff --git a/ydb/core/fq/libs/result_formatter/result_formatter_ut.cpp b/ydb/core/fq/libs/result_formatter/result_formatter_ut.cpp
index 9bd432889b8..f4fcd95007d 100644
--- a/ydb/core/fq/libs/result_formatter/result_formatter_ut.cpp
+++ b/ydb/core/fq/libs/result_formatter/result_formatter_ut.cpp
@@ -103,6 +103,38 @@ Y_UNIT_TEST_SUITE(ResultFormatter) {
         }
     }
 
+    Y_UNIT_TEST(EmptyResultSet) {
+        Ydb::ResultSet rs;
+        {
+            NJson::TJsonValue root;
+            FormatResultSet(root, rs);
+
+            TStringStream stream;
+            NJson::WriteJson(&stream, &root);
+
+            // Cerr << stream.Str() << Endl;
+
+            TString expected = R"___({"data":[],"columns":[]})___";
+
+            UNIT_ASSERT_VALUES_EQUAL(stream.Str(), expected);
+        }
+
+        // pretty format
+        {
+            NJson::TJsonValue root;
+            FormatResultSet(root, rs, true, true);
+
+            TStringStream stream;
+            NJson::WriteJson(&stream, &root);
+
+            // Cerr << stream.Str() << Endl;
+
+            TString expected = R"___({"data":[],"columns":[]})___";
+
+            UNIT_ASSERT_VALUES_EQUAL(stream.Str(), expected);
+        }
+    }
+
     Y_UNIT_TEST(List) {
         Ydb::ResultSet rs;
         {