Restrict DISCARD SELECT in generic query. (KIKIMR-7076)

2 files changed, 21 insertions, 1 deletions

diff --git a/ydb/core/kqp/provider/yql_kikimr_exec.cpp b/ydb/core/kqp/provider/yql_kikimr_exec.cpp
index a1c5c46d3b9..0abe22188ad 100644
--- a/ydb/core/kqp/provider/yql_kikimr_exec.cpp
+++ b/ydb/core/kqp/provider/yql_kikimr_exec.cpp
@@ -737,12 +737,21 @@ private:
         }
 
         if (NCommon::HasResOrPullOption(res.Ref(), "ref")) {
-            ctx.AddError(TIssue(ctx.GetPosition(res.Pos()), TStringBuilder() << "refselect isn't supported for Kikimr provider."));
+            ctx.AddError(TIssue(ctx.GetPosition(res.Pos()), TStringBuilder()
+                << "refselect isn't supported for Kikimr provider."));
             return SyncError();
         }
 
         IDataProvider::TFillSettings fillSettings = NCommon::GetFillSettings(res.Ref());
 
+        if (IsIn({EKikimrQueryType::Query, EKikimrQueryType::Script}, SessionCtx->Query().Type)) {
+            if (fillSettings.Discard) {
+                ctx.AddError(YqlIssue(ctx.GetPosition(res.Pos()), TIssuesIds::KIKIMR_BAD_OPERATION, TStringBuilder()
+                    << "DISCARD not supported in YDB queries"));
+                return SyncError();
+            }
+        }
+
         auto* runResult = SessionCtx->Query().Results.FindPtr(exec.Ref().UniqueId());
         if (!runResult) {
             ctx.AddError(TIssue(ctx.GetPosition(exec.Pos()), TStringBuilder() << "KiExecute run result not found."));
diff --git a/ydb/core/kqp/ut/yql/kqp_yql_ut.cpp b/ydb/core/kqp/ut/yql/kqp_yql_ut.cpp
index 0531f598ddb..d8ac2baf90e 100644
--- a/ydb/core/kqp/ut/yql/kqp_yql_ut.cpp
+++ b/ydb/core/kqp/ut/yql/kqp_yql_ut.cpp
@@ -461,6 +461,17 @@ Y_UNIT_TEST_SUITE(KqpYql) {
             29]
         ])", FormatResultSetYson(result.GetResultSet(0)));
     }
+
+    Y_UNIT_TEST(Discard) {
+        auto kikimr = DefaultKikimrRunner();
+        auto db = kikimr.GetQueryClient();
+
+        auto result = db.ExecuteQuery(R"(
+            DISCARD SELECT 1;
+        )", NYdb::NQuery::TTxControl::BeginTx().CommitTx()).ExtractValueSync();
+        UNIT_ASSERT_VALUES_EQUAL_C(result.GetStatus(), EStatus::GENERIC_ERROR, result.GetIssues().ToString());
+        UNIT_ASSERT(HasIssue(result.GetIssues(), NYql::TIssuesIds::KIKIMR_BAD_OPERATION));
+    }
 }
 
 } // namespace NKqp