fix columns set algebra (#1450)

1 files changed, 1 insertions, 4 deletions

diff --git a/ydb/core/tx/columnshard/engines/reader/plain_reader/columns_set.cpp b/ydb/core/tx/columnshard/engines/reader/plain_reader/columns_set.cpp
index 0d05fe444c0..ee95b7e42fa 100644
--- a/ydb/core/tx/columnshard/engines/reader/plain_reader/columns_set.cpp
+++ b/ydb/core/tx/columnshard/engines/reader/plain_reader/columns_set.cpp
@@ -12,12 +12,9 @@ TString TColumnsSet::DebugString() const {
 }
 
 NKikimr::NOlap::NPlainReader::TColumnsSet TColumnsSet::operator-(const TColumnsSet& external) const {
-    if (external.IsEmpty()) {
+    if (external.IsEmpty() || IsEmpty()) {
         return *this;
     }
-    if (IsEmpty()) {
-        return external;
-    }
     TColumnsSet result = *this;
     for (auto&& i : external.ColumnIds) {
         result.ColumnIds.erase(i);