Fix read iterator local snapshot consistency. Fixes #2885. (#3037)

Author: snaury

ydb/core/tx/datashard/datashard.cpp

@@ -2174,6 +2174,12 @@ TDataShard::TPromotePostExecuteEdges TDataShard::PromoteImmediatePostExecuteEdge
                 << " promoting UnprotectedReadEdge to " << version);
             SnapshotManager.PromoteUnprotectedReadEdge(version);
 
+            // Make sure pending distributed transactions are marked incomplete,
+            // since we just protected up to and including version from writes,
+            // we need to make sure new immediate conflicting writes are blocked
+            // and don't perform writes with out-of-order versions.
+            res.HadWrites |= Pipeline.MarkPlannedLogicallyIncompleteUpTo(version, txc);
+
             // We want to promote the complete edge when protected reads are
             // used or when we're already writing something anyway.
             if (res.HadWrites) {

ydb/core/tx/datashard/datashard__read_iterator.cpp

@@ -46,8 +46,8 @@ namespace {
         return a.GetStep() < b.Step || (a.GetStep() == b.Step && a.GetTxId() < b.TxId);
     }
 
-    bool IsLessEqual(const TOperation& a, const TRowVersion& b) {
-        return a.GetStep() < b.Step || (a.GetStep() == b.Step && a.GetTxId() <= b.TxId);
+    bool IsEqual(const TOperation& a, const TRowVersion& b) {
+        return a.GetStep() == b.Step && a.GetTxId() == b.TxId;
     }
 }
 
@@ -799,8 +799,10 @@ void TDependencyTracker::TMvccDependencyTrackingLogic::AddOperation(const TOpera
         Y_ABORT_UNLESS(!conflict.IsImmediate());
         if (snapshot.IsMax()) {
             conflict.AddImmediateConflict(op);
-        } else if (snapshotRepeatable ? IsLessEqual(conflict, snapshot) : IsLess(conflict, snapshot)) {
+        } else if (IsLess(conflict, snapshot)) {
             op->AddDependency(&conflict);
+        } else if (IsEqual(conflict, snapshot)) {
+            op->AddRepeatableReadConflict(&conflict);
         }
     };
 

ydb/core/tx/datashard/datashard_dep_tracker.cpp

@@ -39,6 +39,7 @@ TPipeline::~TPipeline()
         pr.second->ClearSpecialDependencies();
         pr.second->ClearPlannedConflicts();
         pr.second->ClearImmediateConflicts();
+        pr.second->ClearRepeatableReadConflicts();
     }
 }
 
@@ -487,6 +488,7 @@ void TPipeline::UnblockNormalDependencies(const TOperation::TPtr &op)
     op->ClearDependencies();
     op->ClearPlannedConflicts();
     op->ClearImmediateConflicts();
+    op->ClearRepeatableReadConflicts();
     DepTracker.RemoveOperation(op);
 }
 

ydb/core/tx/datashard/datashard_pipeline.cpp

@@ -208,9 +208,13 @@ namespace NKqpHelpers {
         return FormatResult(result);
     }
 
-    inline TString KqpSimpleCommit(TTestActorRuntime& runtime, const TString& sessionId, const TString& txId, const TString& query) {
+    inline auto KqpSimpleSendCommit(TTestActorRuntime& runtime, const TString& sessionId, const TString& txId, const TString& query) {
         Y_ABORT_UNLESS(!txId.empty(), "commit on empty transaction");
-        auto response = AwaitResponse(runtime, SendRequest(runtime, MakeSimpleRequestRPC(query, sessionId, txId, true /* commitTx */)));
+        return SendRequest(runtime, MakeSimpleRequestRPC(query, sessionId, txId, true /* commitTx */));
+    }
+
+    inline TString KqpSimpleCommit(TTestActorRuntime& runtime, const TString& sessionId, const TString& txId, const TString& query) {
+        auto response = AwaitResponse(runtime, KqpSimpleSendCommit(runtime, sessionId, txId, query));
         if (response.operation().status() != Ydb::StatusIds::SUCCESS) {
             return TStringBuilder() << "ERROR: " << response.operation().status();
         }