KVStore: Log when meets any commit_ts < observed max_read_tso (#8991)

dbms/src/Storages/DeltaMerge/DeltaMergeStore.cpp

@@ -554,7 +554,33 @@ DM::WriteResult DeltaMergeStore::write(const Context & db_context, const DB::Set
         {
             dedup_ver.insert(v);
         }
+<<<<<<< HEAD
         LOG_DEBUG(log, "Record count: {}, Versions: {}", block.rows(), dedup_ver);
+=======
+
+        std::unordered_set<Int64> dedup_handles;
+        auto extra_handle_col = tryGetByColumnId(block, EXTRA_HANDLE_COLUMN_ID);
+        if (extra_handle_col.column)
+        {
+            if (extra_handle_col.type->getTypeId() == TypeIndex::Int64)
+            {
+                const auto * extra_handles = toColumnVectorDataPtr<Int64>(extra_handle_col.column);
+                for (auto h : *extra_handles)
+                {
+                    dedup_handles.insert(h);
+                }
+            }
+        }
+
+        LOG_DEBUG(
+            log,
+            "region_id={} applied_index={} record_count={} versions={} handles={}",
+            applied_status.region_id,
+            applied_status.applied_index,
+            block.rows(),
+            dedup_ver,
+            dedup_handles);
+>>>>>>> 89d1d73883 (KVStore: Log when meets any commit_ts < observed max_read_tso (#8991))
     }
     const auto bytes = block.bytes();
 

dbms/src/Storages/KVStore/Decode/PartitionStreams.cpp

@@ -349,10 +349,34 @@ std::optional<RegionDataReadInfoList> ReadRegionCommitCache(const RegionPtr & re
 
     RegionDataReadInfoList data_list_read;
     data_list_read.reserve(scanner.writeMapSize());
+    auto read_tso = region->getLastObservedReadTso();
+    Timestamp min_error_commit_tso = std::numeric_limits<Timestamp>::max();
+    size_t error_prone_count = 0;
     do
     {
-        data_list_read.emplace_back(scanner.next());
+        // A read index request with read_tso will stop concurrency manager from committing txns with smaller tso by advancing max_ts to at least read_tso.
+        auto data_read = scanner.next();
+        // It's a natual fallback when there has not been any read_tso on this region.
+        if (data_read.commit_ts <= read_tso)
+        {
+            error_prone_count++;
+            min_error_commit_tso = std::min(min_error_commit_tso, data_read.commit_ts);
+        }
+        data_list_read.emplace_back(std::move(data_read));
     } while (scanner.hasNext());
+    if unlikely (error_prone_count > 0)
+    {
+        LOG_INFO(
+            DB::Logger::get(),
+            "Error prone txn commit, tot_count={} error_prone_count={} min_error_commit_tso={} read_tso={} "
+            "region_id={} applied_index={}",
+            data_list_read.size(),
+            error_prone_count,
+            min_error_commit_tso,
+            read_tso,
+            region->id(),
+            region->appliedIndex());
+    }
     return data_list_read;
 }
 

dbms/src/Storages/KVStore/Read/LearnerReadWorker.cpp

@@ -352,6 +352,8 @@ void LearnerReadWorker::waitIndex(
 
         const auto & region = regions_snapshot.find(region_to_query.region_id)->second;
 
+        region->observeLearnerReadEvent(mvcc_query_info.start_ts);
+
         const auto total_wait_index_elapsed_ms = watch.elapsedMilliseconds();
         const auto index_to_wait = batch_read_index_result.find(region_to_query.region_id)->second.read_index();
         if (timeout_ms != 0 && total_wait_index_elapsed_ms > timeout_ms)

dbms/src/Storages/KVStore/Region.cpp

@@ -396,4 +396,20 @@ void Region::mergeDataFrom(const Region & other)
     this->data.mergeFrom(other.data);
     this->data.orphan_keys_info.mergeFrom(other.data.orphan_keys_info);
 }
+
+void Region::observeLearnerReadEvent(Timestamp read_tso) const
+{
+    auto ori = last_observed_read_tso.load();
+    if (read_tso > ori)
+    {
+        // Do not retry if failed, though may lost some update here, however the total read_tso can advance.
+        last_observed_read_tso.compare_exchange_strong(ori, read_tso);
+    }
+}
+
+Timestamp Region::getLastObservedReadTso() const
+{
+    return last_observed_read_tso.load();
+}
+
 } // namespace DB

dbms/src/Storages/KVStore/Region.h

@@ -261,6 +261,8 @@ class Region : public std::enable_shared_from_this<Region>
     // Methods to handle orphan keys under raftstore v2.
     void beforePrehandleSnapshot(uint64_t region_id, std::optional<uint64_t> deadline_index);
     void afterPrehandleSnapshot(int64_t ongoing);
+    void observeLearnerReadEvent(Timestamp read_tso) const;
+    Timestamp getLastObservedReadTso() const;
 
 private:
     friend class RegionRaftCommandDelegate;
@@ -311,6 +313,7 @@ class Region : public std::enable_shared_from_this<Region>
     UInt64 last_restart_log_applied{0};
     mutable std::atomic<size_t> approx_mem_cache_rows{0};
     mutable std::atomic<size_t> approx_mem_cache_bytes{0};
+    mutable std::atomic<Timestamp> last_observed_read_tso{0};
 };
 
 class RegionRaftCommandDelegate