fix.

1 files changed, 7 insertions, 8 deletions

diff --git a/ydb/library/yql/core/common_opt/yql_co_simple1.cpp b/ydb/library/yql/core/common_opt/yql_co_simple1.cpp
index 619f0696447..d2bbe59db5e 100644
--- a/ydb/library/yql/core/common_opt/yql_co_simple1.cpp
+++ b/ydb/library/yql/core/common_opt/yql_co_simple1.cpp
@@ -135,18 +135,17 @@ TExprNode::TPtr KeepSortedConstraint(TExprNode::TPtr node, const TSortedConstrai
 TExprNode::TPtr KeepConstraints(TExprNode::TPtr node, const TExprNode& src, TExprContext& ctx) {
     auto res = KeepSortedConstraint(node, src.GetConstraint<TSortedConstraintNode>(), ctx);
     if (const auto uniq = src.GetConstraint<TUniqueConstraintNode>()) {
-        for (const auto& set : uniq->GetAllSets()) {
+        TExprNode::TListType columns;
+        for (const auto& set : uniq->GetAllSets())
+            for (const auto& path : set)
+                if (!path.empty())
+                    columns.emplace_back(ctx.NewAtom(node->Pos(), path.front()));
+        if (!columns.empty()) { // TODO: AssumeUnique must support any set of columns.
             res = ctx.Builder(node->Pos())
                 .Callable("AssumeUnique")
                     .Add(0, std::move(res))
                     .List(1)
-                        .Do([&](TExprNodeBuilder& parent) -> TExprNodeBuilder& {
-                            size_t index = 0;
-                            for (const auto& path : set) {
-                                parent.Atom(index++, path.front());
-                            }
-                            return parent;
-                        })
+                        .Add(std::move(columns))
                     .Seal()
                 .Seal()
                 .Build();