Closes #4606: fix 42P16 inherited-FK on eager-apply + sharded per-tenant events

src/Marten/Events/Schema/EventsTable.cs

@@ -69,14 +69,40 @@ public EventsTable(EventGraph events): base(new PostgresqlObjectName(events.Data
 
         if (events.TenancyStyle == TenancyStyle.Conjoined)
         {
+            // #4606: under UseTenantPartitionedEvents, mt_events is itself a partitioned
+            // table (by tenant_id) and so is mt_streams. Declaring a parent-level FK from
+            // mt_events → mt_streams makes Postgres auto-propagate a partition-targeting
+            // FK (mt_events → mt_streams_<tenant>) into mt_events as an INHERITED constraint
+            // the moment the first mt_streams_<tenant> partition is attached. The next
+            // mt_events_<tenant> partition-attach then trips
+            // `42P16: cannot drop inherited constraint` because Weasel's
+            // additivelyMigrateTablesForNewPartitions treats the auto-propagated FK as an
+            // "extra" (not in Marten's declared FK set) and tries to drop it, which
+            // Postgres refuses on an inherited constraint. The downstream symptom is
+            // 23514 on the first event append because the partition attach was silently
+            // swallowed by the migration's catch block.
+            //
+            // Skipping the explicit FK trades database-level referential integrity from
+            // mt_events to mt_streams for the per-tenant-partitioning combination
+            // working at all. Marten's append path always inserts/updates the stream row
+            // before persisting events, so application-level integrity is preserved;
+            // external tooling that writes mt_events directly without ensuring the
+            // stream exists in mt_streams is the only at-risk path, and that's already
+            // outside Marten's contract. The non-partitioned and archived-partitioning
+            // shapes keep their FK because they don't trigger the auto-propagation.
+            var skipMtEventsFkForTenantPartitioning = events.UseTenantPartitionedEvents;
+
             if (events.UseArchivedStreamPartitioning)
             {
-                ForeignKeys.Add(new ForeignKey("fkey_mt_events_stream_id_tenant_id_is_archived")
+                if (!skipMtEventsFkForTenantPartitioning)
                 {
-                    ColumnNames = new[] { TenantIdColumn.Name, "stream_id", "is_archived" },
-                    LinkedNames = new[] { TenantIdColumn.Name, "id", "is_archived" },
-                    LinkedTable = new PostgresqlObjectName(events.DatabaseSchemaName, "mt_streams")
-                });
+                    ForeignKeys.Add(new ForeignKey("fkey_mt_events_stream_id_tenant_id_is_archived")
+                    {
+                        ColumnNames = new[] { TenantIdColumn.Name, "stream_id", "is_archived" },
+                        LinkedNames = new[] { TenantIdColumn.Name, "id", "is_archived" },
+                        LinkedTable = new PostgresqlObjectName(events.DatabaseSchemaName, "mt_streams")
+                    });
+                }
 
                 Indexes.Add(new IndexDefinition("pk_mt_events_stream_and_version")
                 {
@@ -85,12 +111,15 @@ public EventsTable(EventGraph events): base(new PostgresqlObjectName(events.Data
             }
             else
             {
-                ForeignKeys.Add(new ForeignKey("fkey_mt_events_stream_id_tenant_id")
+                if (!skipMtEventsFkForTenantPartitioning)
                 {
-                    ColumnNames = new[] { TenantIdColumn.Name, "stream_id" },
-                    LinkedNames = new[] { TenantIdColumn.Name, "id" },
-                    LinkedTable = new PostgresqlObjectName(events.DatabaseSchemaName, "mt_streams")
-                });
+                    ForeignKeys.Add(new ForeignKey("fkey_mt_events_stream_id_tenant_id")
+                    {
+                        ColumnNames = new[] { TenantIdColumn.Name, "stream_id" },
+                        LinkedNames = new[] { TenantIdColumn.Name, "id" },
+                        LinkedTable = new PostgresqlObjectName(events.DatabaseSchemaName, "mt_streams")
+                    });
+                }
 
                 Indexes.Add(new IndexDefinition("pk_mt_events_stream_and_version")
                 {

src/MultiTenancyTests/sharded_eager_apply_per_tenant_events_tests.cs

@@ -0,0 +1,131 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using JasperFx;
+using JasperFx.Events;
+using JasperFx.MultiTenancy;
+using Marten;
+using Marten.Events;
+using Marten.Storage;
+using Marten.Testing.Documents;
+using Marten.Testing.Harness;
+using Npgsql;
+using Shouldly;
+using Weasel.Core;
+using Weasel.Postgresql;
+using Xunit;
+
+namespace MultiTenancyTests;
+
+/// <summary>
+/// #4606 regression — eager schema apply on a sharded + per-tenant-events store,
+/// followed by runtime tenant provisioning, must succeed (no 42P16 on the partition
+/// attach's FK drop).
+///
+/// <para>
+/// The shape this exercises is the production startup pattern:
+///   <c>ApplyAllConfiguredChangesToDatabaseAsync()</c> at boot → tenant arrives later
+///   → <c>AddTenantToShardAsync(tenantId)</c> → first append.
+/// In 9.4.x the FK on the parent <c>mt_events</c> table is inherited the moment
+/// the first partition is attached, and Weasel's partition-attach drop-and-recreate
+/// of that FK trips Postgres' 42P16 (cannot drop inherited constraint). #4598's
+/// tests deliberately exercised the lazy-apply flow to dodge this; #4606 is the
+/// eager-apply variant.
+/// </para>
+/// </summary>
+[Collection("sharded-tenancy")]
+public class sharded_eager_apply_per_tenant_events_tests : IAsyncLifetime
+{
+    private readonly ShardedTenancyFixture _fixture;
+    private IDocumentStore _store = null!;
+
+    public sharded_eager_apply_per_tenant_events_tests(ShardedTenancyFixture fixture)
+    {
+        _fixture = fixture;
+    }
+
+    public async Task InitializeAsync()
+    {
+        await using var conn = new NpgsqlConnection(ConnectionSource.ConnectionString);
+        await conn.OpenAsync();
+        try { await conn.DropSchemaAsync("sharded"); } catch { }
+
+        foreach (var connStr in _fixture.ConnectionStrings.Values)
+        {
+            await using var tenantConn = new NpgsqlConnection(connStr);
+            await tenantConn.OpenAsync();
+            try { await tenantConn.DropSchemaAsync("tenants"); } catch { }
+            await ShardedTenancyFixture.cleanMartenObjectsInPublicSchema(tenantConn);
+        }
+    }
+
+    public Task DisposeAsync()
+    {
+        _store?.Dispose();
+        return Task.CompletedTask;
+    }
+
+    private IDocumentStore CreateStore()
+    {
+        _store = DocumentStore.For(opts =>
+        {
+            opts.MultiTenantedWithShardedDatabases(x =>
+            {
+                x.ConnectionString = ConnectionSource.ConnectionString;
+                x.SchemaName = "sharded";
+                x.PartitionSchemaName = "tenants";
+                foreach (var (dbName, connStr) in _fixture.ConnectionStrings)
+                {
+                    x.AddDatabase(dbName, connStr);
+                }
+                x.UseSmallestDatabaseAssignment();
+            });
+
+            opts.AutoCreateSchemaObjects = AutoCreate.All;
+            opts.Events.TenancyStyle = TenancyStyle.Conjoined;
+            opts.Events.AppendMode = EventAppendMode.QuickWithServerTimestamps;
+            opts.Events.UseTenantPartitionedEvents = true;
+            opts.Events.AddEventType<ShardedTestEvent>();
+        });
+
+        return _store;
+    }
+
+    [Fact]
+    public async Task eager_apply_then_AddTenantToShardAsync_then_append_succeeds()
+    {
+        CreateStore();
+
+        // The eager-apply pattern: create the parent partitioned schema on every
+        // shard at startup time, BEFORE any tenant is provisioned. This is the
+        // startup-migrate deployment shape that #4606 needs to support.
+        var databases = await _store.Options.Tenancy.BuildDatabases();
+        foreach (var db in databases.OfType<IMartenDatabase>())
+        {
+            await db.ApplyAllConfiguredChangesToDatabaseAsync();
+        }
+
+        // Runtime tenant provisioning hits the partition-attach path against an
+        // already-created parent mt_events. Master fails here with
+        // 42P16 cannot drop inherited constraint "mt_events_tenant_id_stream_id_fkey".
+        var dbId = await _store.Advanced.AddTenantToShardAsync("alpha", CancellationToken.None);
+        dbId.ShouldNotBeNull();
+
+        // The actual user-facing failure surface: first append for the new tenant.
+        // On master this throws either the same 42P16 (the attach was silently
+        // swallowed and the partition is missing) or a downstream 23514 (no
+        // partition of relation mt_events found for row).
+        await using var session = _store.LightweightSession("alpha");
+        session.Events.StartStream(Guid.NewGuid(), new ShardedTestEvent { Value = "eager-apply-then-tenant" });
+        await session.SaveChangesAsync();
+
+        // Sanity: the partition lives in the assigned shard.
+        await using var conn = new NpgsqlConnection(_fixture.ConnectionStrings[dbId]);
+        await conn.OpenAsync();
+        var tables = await conn.ExistingTablesAsync();
+        tables.Any(t => t.Name == "mt_events_alpha").ShouldBeTrue(
+            $"mt_events_alpha partition must exist after eager-apply + runtime tenant. Tables: {string.Join(", ", tables.Select(t => t.QualifiedName))}");
+    }
+}