fail gracefully on SHOW CREATE TABLE targeting a view (#16423)

Author: jepett0

ydb/core/kqp/provider/yql_kikimr_datasource.cpp

@@ -9,6 +9,7 @@
 
 #include <yql/essentials/core/yql_expr_optimize.h>
 #include <yql/essentials/core/yql_expr_type_annotation.h>
+#include <yql/essentials/core/yql_opt_utils.h>
 #include <yql/essentials/providers/common/schema/expr/yql_expr_schema.h>
 #include <ydb/library/yql/providers/dq/expr_nodes/dqs_expr_nodes.h>
 #include <ydb/library/yql/dq/expr_nodes/dq_expr_nodes.h>
@@ -95,6 +96,15 @@ namespace {
 using namespace NKikimr;
 using namespace NNodes;
 
+bool IsShowCreate(const TExprNode& read) {
+    if (read.ChildrenSize() <= TKiReadTable::idx_Settings) {
+        return false;
+    }
+    const auto& settings = *read.Child(TKiReadTable::idx_Settings);
+    return HasSetting(settings, "showCreateTable")
+        || HasSetting(settings, "showCreateView");
+}
+
 class TKiSourceIntentDeterminationTransformer: public TKiSourceVisitorTransformer {
 public:
     TKiSourceIntentDeterminationTransformer(TIntrusivePtr<TKikimrSessionContext> sessionCtx)
@@ -795,7 +805,7 @@ class TKikimrDataSource : public TDataProviderBase {
                     retChildren[0] = newRead;
                     return ctx.ChangeChildren(*node, std::move(retChildren));
                 }
-            } else if (tableDesc.Metadata->Kind == EKikimrTableKind::View) {
+            } else if (tableDesc.Metadata->Kind == EKikimrTableKind::View && !IsShowCreate(*read)) {
                 if (!SessionCtx->Config().FeatureFlags.GetEnableViews()) {
                     ctx.AddError(TIssue(node->Pos(ctx),
                                         "Views are disabled. Please contact your system administrator to enable the feature"));

ydb/core/kqp/ut/service/kqp_qs_queries_ut.cpp

@@ -2895,6 +2895,31 @@ Y_UNIT_TEST_SUITE(KqpQueryService) {
         }
     }
 
+    Y_UNIT_TEST(ShowCreateTableOnView) {
+        auto serverSettings = TKikimrSettings().SetEnableShowCreate(true);
+
+        TKikimrRunner kikimr(serverSettings);
+        auto db = kikimr.GetQueryClient();
+        auto session = db.GetSession().GetValueSync().GetSession();
+
+        {
+            // note: KeyValue is one of the sample tables created in KikimrRunner
+            auto result = session.ExecuteQuery(R"(
+                CREATE VIEW test_view WITH security_invoker = TRUE AS
+                    SELECT * FROM KeyValue;
+            )", TTxControl::NoTx()).ExtractValueSync();
+            UNIT_ASSERT_VALUES_EQUAL_C(result.GetStatus(), EStatus::SUCCESS, result.GetIssues().ToString());
+        }
+
+        {
+            auto result = session.ExecuteQuery(R"(
+                SHOW CREATE TABLE test_view;
+            )", TTxControl::NoTx()).ExtractValueSync();
+            UNIT_ASSERT_VALUES_EQUAL_C(result.GetStatus(), EStatus::ABORTED, result.GetIssues().ToString());
+            UNIT_ASSERT_STRING_CONTAINS(result.GetIssues().ToString(), "Invalid path type");
+        }
+    }
+
     Y_UNIT_TEST(DdlCache) {
         NKikimrConfig::TAppConfig appConfig;
         auto setting = NKikimrKqp::TKqpSetting();