Enable sequential reads by default

4 files changed, 5 insertions, 6 deletions

diff --git a/ydb/core/kqp/executer_actor/kqp_executer_impl.h b/ydb/core/kqp/executer_actor/kqp_executer_impl.h
index be19b632a9..e91cddd480 100644
--- a/ydb/core/kqp/executer_actor/kqp_executer_impl.h
+++ b/ydb/core/kqp/executer_actor/kqp_executer_impl.h
@@ -906,10 +906,10 @@ protected:
             BuildSinks(stage, task, secureParams);
         };
 
-        if (source.GetSequentialInFlightShards()) {
+        THashMap<ui64, TShardInfo> partitions = PrunePartitions(source, stageInfo, HolderFactory(), TypeEnv());
+        if (partitions.size() > 0 && source.GetSequentialInFlightShards() > 0 && partitions.size() > source.GetSequentialInFlightShards()) {
             auto [startShard, shardInfo] = MakeVirtualTablePartition(source, stageInfo, HolderFactory(), TypeEnv());
             if (Stats) {
-                THashMap<ui64, TShardInfo> partitions = PrunePartitions(source, stageInfo, HolderFactory(), TypeEnv());
                 for (auto& [shardId, _] : partitions) {
                     Stats->AffectedShards.insert(shardId);
                 }
@@ -921,7 +921,6 @@ protected:
                 return 0;
             }
         } else {
-            THashMap<ui64, TShardInfo> partitions = PrunePartitions(source, stageInfo, HolderFactory(), TypeEnv());
             for (auto& [shardId, shardInfo] : partitions) {
                 addPartiton(shardId, shardId, shardInfo, {});
             }
diff --git a/ydb/core/kqp/ut/perf/kqp_query_perf_ut.cpp b/ydb/core/kqp/ut/perf/kqp_query_perf_ut.cpp
index a34b71bff0..f4ed0ed280 100644
--- a/ydb/core/kqp/ut/perf/kqp_query_perf_ut.cpp
+++ b/ydb/core/kqp/ut/perf/kqp_query_perf_ut.cpp
@@ -272,7 +272,7 @@ Y_UNIT_TEST_SUITE(KqpQueryPerf) {
         for (const auto& stage : stages) {
             totalTasks += stage.GetMapSafe().at("Stats").GetMapSafe().at("TotalTasks").GetIntegerSafe();
         }
-        UNIT_ASSERT_VALUES_EQUAL(totalTasks, 3);
+        UNIT_ASSERT_VALUES_EQUAL(totalTasks, EnableSourceRead ? 2 : 3);
     }
 
     Y_UNIT_TEST(Upsert) {
diff --git a/ydb/core/protos/config.proto b/ydb/core/protos/config.proto
index 228efda1d1..07b5fe3d94 100644
--- a/ydb/core/protos/config.proto
+++ b/ydb/core/protos/config.proto
@@ -1352,7 +1352,7 @@ message TTableServiceConfig {
     optional bool EnablePredicateExtractForScanQueries = 36 [default = true];
     optional bool EnablePredicateExtractForDataQueries = 37 [default = true];
     optional bool EnableKqpImmediateEffects = 38 [default = true];
-    optional bool EnableSequentialReads = 39 [default = false];
+    optional bool EnableSequentialReads = 39 [default = true];
     optional bool EnablePreparedDdl = 42 [default = false];
     optional bool EnableSequences = 43 [default = true];
     optional bool EnableAsyncComputationPatternCompilation = 48 [default = false];
diff --git a/ydb/core/sys_view/ut_kqp.cpp b/ydb/core/sys_view/ut_kqp.cpp
index e7e9e2e7d8..55f9803bc5 100644
--- a/ydb/core/sys_view/ut_kqp.cpp
+++ b/ydb/core/sys_view/ut_kqp.cpp
@@ -607,7 +607,7 @@ Y_UNIT_TEST_SUITE(SystemView) {
         check.Uint64GreaterOrEquals(0); // CPUTime
         check.Uint64GreaterOrEquals(0); // CompileCPUTime
         check.Int64GreaterOrEquals(0); // CompileDuration
-        check.Uint64(iterators ? 4 : 1); // ComputeNodesCount
+        check.Uint64(iterators ? 2 : 1); // ComputeNodesCount
         check.Uint64(0); // DeleteBytes
         check.Uint64(0); // DeleteRows
         check.Int64Greater(0); // Duration