From a5e50872603cd3ffef18bb08eb4553947dde6be8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?V=C3=ADctor=20Rold=C3=A1n=20Betancort?=
 <vroldanbet@authzed.com>
Date: Fri, 29 Nov 2024 15:39:49 +0000
Subject: [PATCH 1/2] repro: namespace/caveat changes cause an incorrect delete
 event

---
 pkg/datastore/test/watch.go | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/pkg/datastore/test/watch.go b/pkg/datastore/test/watch.go
index e36b02973b..40b9e7aa58 100644
--- a/pkg/datastore/test/watch.go
+++ b/pkg/datastore/test/watch.go
@@ -537,6 +537,7 @@ func WatchSchemaTest(t *testing.T, tester DatastoreTester) {
 	changes, errchan := ds.Watch(ctx, lowestRevision, datastore.WatchJustSchema())
 	require.Zero(len(errchan))
 
+	// Addition
 	// Write an updated schema and ensure the changes are returned.
 	_, err = ds.ReadWriteTx(ctx, func(ctx context.Context, rwt datastore.ReadWriteTransaction) error {
 		err := rwt.WriteNamespaces(ctx, &core.NamespaceDefinition{
@@ -561,6 +562,37 @@ func WatchSchemaTest(t *testing.T, tester DatastoreTester) {
 		},
 	}, changes, errchan, false)
 
+	// Changed
+	_, err = ds.ReadWriteTx(ctx, func(ctx context.Context, rwt datastore.ReadWriteTransaction) error {
+		err := rwt.WriteNamespaces(ctx, &core.NamespaceDefinition{
+			Name: "somenewnamespace",
+			Relation: []*core.Relation{
+				{
+					Name: "anotherrelation",
+				},
+			},
+		})
+		if err != nil {
+			return err
+		}
+
+		return rwt.WriteCaveats(ctx, []*core.CaveatDefinition{
+			{
+				Name:                 "somenewcaveat",
+				SerializedExpression: []byte("123"),
+			},
+		})
+	})
+	require.NoError(err)
+
+	verifyMixedUpdates(require, [][]string{
+		{
+			"changed:somenewnamespace",
+			"changed:somenewcaveat",
+		},
+	}, changes, errchan, false)
+
+	// Removed
 	// Delete some namespaces and caveats.
 	_, err = ds.ReadWriteTx(ctx, func(ctx context.Context, rwt datastore.ReadWriteTransaction) error {
 		err := rwt.DeleteNamespaces(ctx, "somenewnamespace")

From 369286ec067123040ca7dc3872bfe793647225a4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?V=C3=ADctor=20Rold=C3=A1n=20Betancort?=
 <vroldanbet@authzed.com>
Date: Fri, 29 Nov 2024 15:41:25 +0000
Subject: [PATCH 2/2] fix: namespace/caveat changes cause an incorrect delete
 event

the computation of schema change events was incorrect due to
the use of the wrong snapshot XID for changed namespaces / caveats.
It manifested itself as a change event, followed by a delete event.
---
 internal/datastore/postgres/watch.go | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/internal/datastore/postgres/watch.go b/internal/datastore/postgres/watch.go
index d91e2fa78c..d8a8253bdc 100644
--- a/internal/datastore/postgres/watch.go
+++ b/internal/datastore/postgres/watch.go
@@ -455,7 +455,7 @@ func (pgd *pgDatastore) loadNamespaceChanges(ctx context.Context, xmin uint64, x
 		}
 
 		if _, found := filter[createdXID.Uint64]; found {
-			err := tracked.AddChangedDefinition(ctx, txidToRevision[deletedXID.Uint64], loaded)
+			err := tracked.AddChangedDefinition(ctx, txidToRevision[createdXID.Uint64], loaded)
 			if err != nil {
 				return err
 			}
@@ -514,7 +514,7 @@ func (pgd *pgDatastore) loadCaveatChanges(ctx context.Context, xmin uint64, xmax
 		}
 
 		if _, found := filter[createdXID.Uint64]; found {
-			err := tracked.AddChangedDefinition(ctx, txidToRevision[deletedXID.Uint64], loaded)
+			err := tracked.AddChangedDefinition(ctx, txidToRevision[createdXID.Uint64], loaded)
 			if err != nil {
 				return err
 			}