Check missing fields in Cast constraints calculation

commit_hash:80d14b9a81504ea3fcb8d6fa89a2472f700c0f0e

2 files changed, 31 insertions, 3 deletions

diff --git a/yql/essentials/core/ut/yql_expr_constraint_ut.cpp b/yql/essentials/core/ut/yql_expr_constraint_ut.cpp
index 45d9f6285de..a4145b9c5a8 100644
--- a/yql/essentials/core/ut/yql_expr_constraint_ut.cpp
+++ b/yql/essentials/core/ut/yql_expr_constraint_ut.cpp
@@ -1124,6 +1124,28 @@ Y_UNIT_TEST_SUITE(TYqlExprConstraints) {
         CheckConstraint<TUniqueConstraintNode>(exprRoot, "LazyList", "Unique((one,{two,xxx},yyy))");
     }
 
+    Y_UNIT_TEST(UniqueNarrowCast) {
+        const auto s = R"((
+            (let res (DataSink 'result))
+            (let list (AsList
+                (AsStruct '('key (String '4)) '('subkey (String 'c)) '('value (String 'x)))
+                (AsStruct '('key (String '1)) '('subkey (String 'b)) '('value (String 'y)))
+                (AsStruct '('key (String '4)) '('subkey (String 'b)) '('value (String 'z)))
+            ))
+            (let list (AssumeUnique list '('key 'subkey)))
+            (let list (Map list (lambda '(item)
+                (SafeCast item (StructType '('key (DataType 'String)) '('value (DataType 'String))))
+            )))
+            (let world (Write! world res (Key) list '()))
+            (let world (Commit! world res))
+            (return world)
+        ))";
+
+        TExprContext exprCtx;
+        const auto exprRoot = ParseAndAnnotate(s, exprCtx);
+        CheckConstraint<TUniqueConstraintNode>(exprRoot, "Map", "");
+    }
+
     Y_UNIT_TEST(Distinct) {
         const auto s = R"((
     (let res (DataSink 'result))
diff --git a/yql/essentials/core/yql_expr_constraint.cpp b/yql/essentials/core/yql_expr_constraint.cpp
index fdfc21946be..e67557d9645 100644
--- a/yql/essentials/core/yql_expr_constraint.cpp
+++ b/yql/essentials/core/yql_expr_constraint.cpp
@@ -665,12 +665,18 @@ private:
         };
 
         const auto filterForUnique = [inItemType, outItemType](const TPartOfConstraintBase::TPathType& path) {
-            const auto castResult = CastResult<Strict>(TPartOfConstraintBase::GetSubTypeByPath(path, *inItemType), TPartOfConstraintBase::GetSubTypeByPath(path, *outItemType));
-            return NUdf::ECastOptions::Complete == castResult || NUdf::ECastOptions::MayFail == castResult;
+            if (const auto outType = TPartOfConstraintBase::GetSubTypeByPath(path, *outItemType)) {
+                const auto castResult = CastResult<Strict>(TPartOfConstraintBase::GetSubTypeByPath(path, *inItemType), outType);
+                return NUdf::ECastOptions::Complete == castResult || NUdf::ECastOptions::MayFail == castResult;
+            }
+            return false;
         };
 
         const auto filterForDistinct = [inItemType, outItemType](const TPartOfConstraintBase::TPathType& path) {
-            return NUdf::ECastOptions::Complete == CastResult<Strict>(TPartOfConstraintBase::GetSubTypeByPath(path, *inItemType), TPartOfConstraintBase::GetSubTypeByPath(path, *outItemType));
+            if (const auto outType = TPartOfConstraintBase::GetSubTypeByPath(path, *outItemType)) {
+                return NUdf::ECastOptions::Complete == CastResult<Strict>(TPartOfConstraintBase::GetSubTypeByPath(path, *inItemType), outType);
+            }
+            return false;
         };
 
         FilterFromHead<TSortedConstraintNode>(input, filter, ctx);