fix(core): do not issue extra updates when there are no matching chan…

…gesets

Closes #5510

packages/core/src/unit-of-work/UnitOfWork.ts

@@ -531,6 +531,18 @@ export class UnitOfWork {
       return;
     }
 
+    let conflicts = false;
+
+    for (const cs of this.changeSets.values()) {
+      if (cs.rootName === changeSet.rootName) {
+        conflicts = true;
+      }
+    }
+
+    if (!conflicts) {
+      return;
+    }
+
     this.extraUpdates.add([changeSet.entity, props.map(p => p.name), props.map(p => changeSet.entity[p.name]), changeSet]);
 
     for (const p of props) {

tests/issues/GH5510.test.ts

@@ -0,0 +1,63 @@
+import { MikroORM, Entity, OneToOne, PrimaryKey, Property } from '@mikro-orm/postgresql';
+import { mockLogger } from '../helpers';
+
+@Entity()
+class Other {
+
+  @PrimaryKey()
+  id!: number;
+
+  @Property()
+  name!: string;
+
+  @Property({ nullable: true, onUpdate: () => new Date() })
+  updatedAt?: Date;
+
+}
+
+@Entity()
+class Test {
+
+  @PrimaryKey()
+  id!: number;
+
+  @Property()
+  name!: string;
+
+  @Property({ nullable: true, onUpdate: () => new Date() })
+  updatedAt?: Date;
+
+  @OneToOne(() => Other, { nullable: true })
+  other?: Other;
+
+}
+
+let orm: MikroORM;
+
+beforeAll(async () => {
+  orm = await MikroORM.init({
+    dbName: '5510',
+    entities: [Test],
+  });
+  await orm.schema.refreshDatabase();
+});
+
+afterAll(async () => {
+  await orm.close(true);
+});
+
+it('should merge all changes of one record into one sql update statement', async () => {
+  const tid = await orm.em.insert(Test, { name: 'Foo' });
+  const test = await orm.em.findOne(Test, { id: tid });
+
+  const other = new Other();
+  other.name = 'Foo';
+  test!.other = other;
+
+  const mock = mockLogger(orm);
+  await orm.em.flush();
+
+  expect(mock.mock.calls).toHaveLength(
+    [['begin'], ['insert into other'], ['update test'], ['commit']].length,
+  );
+});