diff --git a/backend/src/db/migrations/20251011141618_membership-identity-index.ts b/backend/src/db/migrations/20251011141618_membership-identity-index.ts
new file mode 100644
index 000000000..8d33b61a0
--- /dev/null
+++ b/backend/src/db/migrations/20251011141618_membership-identity-index.ts
@@ -0,0 +1,23 @@
+import { Knex } from "knex";
+
+import { TableName } from "../schemas";
+
+export async function up(knex: Knex): Promise<void> {
+  const hasScopeColumn = await knex.schema.hasColumn(TableName.Membership, "scope");
+  const hasActorIdentityColumn = await knex.schema.hasColumn(TableName.Membership, "actorIdentityId");
+  if (hasScopeColumn && hasActorIdentityColumn) {
+    await knex.schema.alterTable(TableName.Membership, (t) => {
+      t.index(["scope", "actorIdentityId"]);
+    });
+  }
+}
+
+export async function down(knex: Knex): Promise<void> {
+  const hasScopeColumn = await knex.schema.hasColumn(TableName.Membership, "scope");
+  const hasActorIdentityColumn = await knex.schema.hasColumn(TableName.Membership, "actorIdentityId");
+  if (hasScopeColumn && hasActorIdentityColumn) {
+    await knex.schema.alterTable(TableName.Membership, (t) => {
+      t.dropIndex(["scope", "actorIdentityId"]);
+    });
+  }
+}