From 5c0a85fe7c0344466926b10c53db3ee53213e346 Mon Sep 17 00:00:00 2001
From: Pisarenko Grigoriy <grigoriypisar@ydb.tech>
Date: Fri, 31 Oct 2025 18:19:20 +0300
Subject: [PATCH 1/2] Fixed uncaught exception in external sources explain

---
 ydb/core/kqp/session_actor/kqp_session_actor.cpp | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/ydb/core/kqp/session_actor/kqp_session_actor.cpp b/ydb/core/kqp/session_actor/kqp_session_actor.cpp
index 60b79ab89bb8..b61115e38a61 100644
--- a/ydb/core/kqp/session_actor/kqp_session_actor.cpp
+++ b/ydb/core/kqp/session_actor/kqp_session_actor.cpp
@@ -789,6 +789,7 @@ class TKqpSessionActor : public TActorBootstrapped<TKqpSessionActor>, IActorExce
     void OnSuccessCompileRequest() {
         if (QueryState->GetAction() == NKikimrKqp::QUERY_ACTION_EXPLAIN) {
             TVector<IKqpGateway::TPhysicalTxData> txs;
+            std::map<TString, TString> secureParams;
             bool isValidParams = true;
             auto txAlloc = std::make_shared<TTxAllocatorState>(AppData()->FunctionRegistry, AppData()->TimeProvider, AppData()->RandomProvider);
             const auto& parameters = QueryState->GetYdbParameters();
@@ -796,6 +797,10 @@ class TKqpSessionActor : public TActorBootstrapped<TKqpSessionActor>, IActorExce
             QueryState->QueryData->ParseParameters(parameters);
 
             for (const auto& tx : QueryState->PreparedQuery->GetTransactions()) {
+                for (const auto& secretName : tx->GetSecretNames()) {
+                    secureParams.emplace(secretName, "");
+                }
+
                 txs.emplace_back(tx, QueryState->QueryData);
                 try {
                     QueryState->QueryData->PrepareParameters(tx, QueryState->PreparedQuery, txAlloc->TypeEnv);
@@ -810,6 +815,7 @@ class TKqpSessionActor : public TActorBootstrapped<TKqpSessionActor>, IActorExce
                 auto tasksGraph = TKqpTasksGraph(Settings.Database, txs, txAlloc, {}, Settings.TableService.GetAggregationConfig(), RequestCounters, {});
                 tasksGraph.GetMeta().AllowOlapDataQuery = Settings.TableService.GetAllowOlapDataQuery();
                 tasksGraph.GetMeta().UserRequestContext = QueryState ? QueryState->UserRequestContext : MakeIntrusive<TUserRequestContext>("", Settings.Database, SessionId);
+                tasksGraph.GetMeta().SecureParams = std::move(secureParams);
 
                 // Resolve tables
                 {
@@ -871,7 +877,7 @@ class TKqpSessionActor : public TActorBootstrapped<TKqpSessionActor>, IActorExce
                     tasksGraph.BuildAllTasks({}, resourcesSnapshot, nullptr, nullptr);
                     // TODO: fill tasks count into result
                     // Cerr << tasksGraph.DumpToString();
-                } catch (const yexception&) {
+                } catch (const std::exception&) {
                     // TODO: send warning to user that we failed to estimate number of tasks.
                 }
             }

From e88dc3a629e0efdc38ab7ba19ecf0bf74cde1afd Mon Sep 17 00:00:00 2001
From: Pisarenko Grigoriy <grigoriypisar@ydb.tech>
Date: Fri, 31 Oct 2025 18:34:01 +0300
Subject: [PATCH 2/2] Added unit test

---
 .../datastreams/datastreams_ut.cpp            | 26 +++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/ydb/core/kqp/ut/federated_query/datastreams/datastreams_ut.cpp b/ydb/core/kqp/ut/federated_query/datastreams/datastreams_ut.cpp
index 54f2a16271a7..1d8a9f35617e 100644
--- a/ydb/core/kqp/ut/federated_query/datastreams/datastreams_ut.cpp
+++ b/ydb/core/kqp/ut/federated_query/datastreams/datastreams_ut.cpp
@@ -1077,6 +1077,32 @@ Y_UNIT_TEST_SUITE(KqpFederatedQueryDatastreams) {
         }
     }
 
+    Y_UNIT_TEST_F(ExplainReadTopicBasic, TStreamingTestFixture) {
+        const TString sourceName = "sourceName";
+        const TString topicName = "topicName";
+        CreateTopic(topicName);
+
+        CreatePqSourceBasicAuth(sourceName);
+
+        const auto result = GetQueryClient()->ExecuteQuery(fmt::format(
+            "SELECT * FROM `{source}`.`{topic}`",
+            "source"_a=sourceName,
+            "topic"_a=topicName
+        ), TTxControl::NoTx(), TExecuteQuerySettings().ExecMode(EExecMode::Explain)).ExtractValueSync();
+        UNIT_ASSERT_VALUES_EQUAL(result.GetStatus(), EStatus::SUCCESS);
+
+        const auto& stats = result.GetStats();
+        UNIT_ASSERT(stats);
+
+        const auto& plan = stats->GetPlan();
+        UNIT_ASSERT(plan);
+        UNIT_ASSERT_STRING_CONTAINS(*plan, sourceName);
+
+        const auto& ast = stats->GetAst();
+        UNIT_ASSERT(ast);
+        UNIT_ASSERT_STRING_CONTAINS(*ast, sourceName);
+    }
+
     Y_UNIT_TEST_F(InsertTopicBasic, TStreamingTestFixture) {
         TString sourceName = "sourceName";
         TString inputTopicName = "inputTopicName";