update durability code

src/dbms/dbms_handler.cpp

@@ -188,7 +188,8 @@ DbmsHandler::DbmsHandler(storage::Config config, replication::ReplicationState &
   if (flags::AreExperimentsEnabled(flags::Experiments::SYSTEM_REPLICATION) && !recovery_on_startup) {
     // This will result in dropping databases on SystemRecoveryHandler
     // for MT case, and for single DB case we might not even set replication as commit timestamp is checked
-    spdlog::warn("Data recovery on startup not set, this will result in dropping database in case o.");
+    spdlog::warn(
+        "Data recovery on startup not set, this will result in dropping database in case of multi-tenancy enabled.");
   }
 
   // TODO: Problem is if user doesn't set this up "database" name won't be recovered

src/storage/v2/durability/durability.cpp

@@ -414,10 +414,6 @@ std::optional<RecoveryInfo> Recovery::RecoverData(std::string *uuid, Replication
     auto last_loaded_timestamp = snapshot_timestamp;
     spdlog::info("Trying to load WAL files.");
 
-    // This way we skip WALs finalized only because of role change.
-    // We can also set the last timestamp to 0 if last loaded timestamp
-    // is nullopt as this can only happen if the WAL file with seq = 0
-    // does not contain any deltas and we didn't find any snapshots.
     if (last_loaded_timestamp) {
       epoch_history->emplace_back(repl_storage_state.epoch_.id(), *last_loaded_timestamp);
     }
@@ -427,18 +423,7 @@ std::optional<RecoveryInfo> Recovery::RecoverData(std::string *uuid, Replication
         LOG_FATAL("You are missing a WAL file with the sequence number {}!", *previous_seq_num + 1);
       }
       previous_seq_num = wal_file.seq_num;
-      /*
+
-      if (wal_file.epoch_id != repl_storage_state.epoch_.id()) {
-        // This way we skip WALs finalized only because of role change.
-        // We can also set the last timestamp to 0 if last loaded timestamp
-        // is nullopt as this can only happen if the WAL file with seq = 0
-        // does not contain any deltas and we didn't find any snapshots.
-        if (last_loaded_timestamp) {
-          epoch_history->emplace_back(wal_file.epoch_id, *last_loaded_timestamp);
-        }
-        repl_storage_state.epoch_.SetEpoch(std::move(wal_file.epoch_id));
-      }
-       */
       try {
         auto info = LoadWal(wal_file.path, &indices_constraints, last_loaded_timestamp, vertices, edges, name_id_mapper,
                             edge_count, config.salient.items);
@@ -452,24 +437,23 @@ std::optional<RecoveryInfo> Recovery::RecoverData(std::string *uuid, Replication
           last_loaded_timestamp.emplace(recovery_info.next_timestamp - 1);
         }
 
-        auto no_last_element_or_different_epoch =
+        bool epoch_history_empty = epoch_history->empty();
-            (!epoch_history->empty() && epoch_history->back().first != wal_file.epoch_id) || epoch_history->empty();
+        bool epoch_not_recorded = !epoch_history_empty && epoch_history->back().first != wal_file.epoch_id;
-        if (no_last_element_or_different_epoch) {
+        auto last_loaded_timestamp_value = last_loaded_timestamp.value_or(0);
-          epoch_history->emplace_back(std::string(wal_file.epoch_id), last_loaded_timestamp.value_or(0));
+
+        if (epoch_history_empty || epoch_not_recorded) {
+          epoch_history->emplace_back(std::string(wal_file.epoch_id), last_loaded_timestamp_value);
         }
-        auto last_epoch_bigger_timestamp = !epoch_history->empty() &&
+
-                                           epoch_history->back().first == wal_file.epoch_id &&
+        auto last_epoch_updated = !epoch_history_empty && epoch_history->back().first == wal_file.epoch_id &&
-                                           epoch_history->back().second < last_loaded_timestamp.value_or(0);
+                                  epoch_history->back().second < last_loaded_timestamp_value;
-        if (last_epoch_bigger_timestamp) {
+        if (last_epoch_updated) {
-          epoch_history->back().second = last_loaded_timestamp.value_or(0);
+          epoch_history->back().second = last_loaded_timestamp_value;
         }
 
       } catch (const RecoveryFailure &e) {
         LOG_FATAL("Couldn't recover WAL deltas from {} because of: {}", wal_file.path, e.what());
       }
-      if (recovery_info.next_timestamp != 0) {
-        last_loaded_timestamp.emplace(recovery_info.next_timestamp - 1);
-      }
     }
     // The sequence number needs to be recovered even though `LoadWal` didn't
     // load any deltas from that file.

tests/e2e/high_availability/single_coordinator.py

@@ -234,7 +234,7 @@ def test_replication_works_on_failover_replica_1_epoch_2_commits_away(data_recov
     # 5
     interactive_mg_runner.kill(MEMGRAPH_INNER_INSTANCES_DESCRIPTION, "instance_1")
 
-    # 6.
+    # 6
 
     with pytest.raises(Exception) as e:
         execute_and_fetch_all(main_cursor, "CREATE (:EpochVertex1 {prop:2});")
@@ -242,7 +242,7 @@ def test_replication_works_on_failover_replica_1_epoch_2_commits_away(data_recov
 
     assert execute_and_fetch_all(instance_2_cursor, "MATCH (n) RETURN count(n);")[0][0] == 2
 
-    # 7. Kill main
+    # 7
     interactive_mg_runner.kill(MEMGRAPH_INNER_INSTANCES_DESCRIPTION, "instance_3")
 
     # 8.
@@ -259,13 +259,13 @@ def test_replication_works_on_failover_replica_1_epoch_2_commits_away(data_recov
     ]
     mg_sleep_and_assert(expected_data_on_coord, retrieve_data_show_instances)
 
-    # 9. Create vertex on instance 2
+    # 9
 
     with pytest.raises(Exception) as e:
         execute_and_fetch_all(instance_2_cursor, "CREATE (:Epoch3 {prop:3});")
     assert "At least one SYNC replica has not confirmed committing last transaction." in str(e.value)
 
-    # 10. Start instance_1 ( it should have one commit on old epoch and new epoch with new commit shouldn't be replicated)
+    # 10
     interactive_mg_runner.start(MEMGRAPH_INNER_INSTANCES_DESCRIPTION, "instance_1")
 
     new_expected_data_on_coord = [
@@ -276,7 +276,7 @@ def test_replication_works_on_failover_replica_1_epoch_2_commits_away(data_recov
     ]
     mg_sleep_and_assert(new_expected_data_on_coord, retrieve_data_show_instances)
 
-    # 11. Expect data to be copied on instance_1
+    # 11
     instance_1_cursor = connect(host="localhost", port=7688).cursor()
 
     def get_vertex_count():
@@ -284,7 +284,7 @@ def test_replication_works_on_failover_replica_1_epoch_2_commits_away(data_recov
 
     mg_sleep_and_assert(3, get_vertex_count)
 
-    # 12. Start old MAIN (instance_3)
+    # 12
 
     interactive_mg_runner.start(MEMGRAPH_INNER_INSTANCES_DESCRIPTION, "instance_3")
 
@@ -296,7 +296,7 @@ def test_replication_works_on_failover_replica_1_epoch_2_commits_away(data_recov
     ]
     mg_sleep_and_assert(new_expected_data_on_coord, retrieve_data_show_instances)
 
-    # 13. Expect data to be copied to instance_3
+    # 13
 
     instance_3_cursor = connect(host="localhost", port=7687).cursor()
 
@@ -1462,4 +1462,5 @@ def test_disable_multiple_mains():
 
 
 if __name__ == "__main__":
+    sys.exit(pytest.main([__file__, "-k", "test_replication_correct_replica_chosen_up_to_date_data"]))
     sys.exit(pytest.main([__file__, "-rA"]))