Using the tenant id as part of FetchForWriting/Latest when using async projections

Author: jeremydmiller

src/Marten/Events/Fetching/FetchAsyncPlan.cs

@@ -11,6 +11,7 @@
 using Marten.Internal.Storage;
 using Marten.Linq.QueryHandlers;
 using Marten.Schema;
+using Marten.Storage;
 using Npgsql;
 using Weasel.Core;
 using Weasel.Postgresql;
@@ -73,8 +74,18 @@ public FetchAsyncPlan(EventGraph events, IEventIdentityStrategy<TId> identityStr
         _storage = storage;
         _aggregator = _events.Options.Projections.AggregatorFor<TDoc>();
 
-        _versionSelectionSql =
-            $" left outer join {storage.TableName.QualifiedName} as a on d.stream_id = a.id where (a.mt_version is NULL or d.version > a.mt_version) and d.stream_id = ";
+        if (_events.TenancyStyle == TenancyStyle.Single)
+        {
+            _versionSelectionSql =
+                $" left outer join {storage.TableName.QualifiedName} as a on d.stream_id = a.id where (a.mt_version is NULL or d.version > a.mt_version) and d.stream_id = ";
+        }
+        else
+        {
+            _versionSelectionSql =
+                $" left outer join {storage.TableName.QualifiedName} as a on d.stream_id = a.id and d.tenant_id = a.tenant_id where (a.mt_version is NULL or d.version > a.mt_version) and d.stream_id = ";
+        }
+
+
     }
 
     public async Task<IEventStream<TDoc>> FetchForWriting(DocumentSessionBase session, TId id, bool forUpdate, CancellationToken cancellation = default)
@@ -177,6 +188,14 @@ private void writeEventFetchStatement(TId id,
         builder.Append(_initialSql);
         builder.Append(_versionSelectionSql);
         builder.AppendParameter(id);
+
+        // You must do this for performance even if the stream ids were
+        // magically unique across tenants
+        if (_events.TenancyStyle == TenancyStyle.Conjoined)
+        {
+            builder.Append(" and d.tenant_id = ");
+            builder.AppendParameter(builder.TenantId);
+        }
     }
 
     public async Task<IEventStream<TDoc>> FetchForWriting(DocumentSessionBase session, TId id, long expectedStartingVersion,