In the Unity Data-Oriented Technology Stack (DOTS), an EntityQuery acts as a dynamic filter. While components are registered at startup, the archetypes they form can appear at any time. The internal system automatically updates existing EntityQuery instances to include these new archetypes without manual intervention.

• EntityQuery construction is an expensive operation involving hashing and registration within the EntityManager.
• Manual creation via EntityQueryBuilder or GetEntityQuery should be performed exclusively inside OnCreate.
• The SystemAPI.Query method used in OnUpdate is a specialized case where the Unity Source Generator creates and caches the EntityQuery at compile-time.
• Creating a new EntityQueryBuilder inside OnUpdate will result in significant memory allocations and CPU overhead every frame.

Additional Tips

• For scenarios requiring runtime logic changes, pre-define all possible queries in OnCreate and store them in a NativeList or array.
• Use RequireForUpdate with your cached EntityQuery to prevent systems from running when specific data is missing.
• If utilizing ISystem, ensure you store the EntityQuery handle in the system state or as a member variable.