Hello, Goal: I'm trying to create a ring buffer of entities in Unity DOTS while minimizing sync points, e.g. while using an entity command buffer (ECB). Failed plan: My plan was to use an ECB to append entities (wrapped in buffer elements) to a dynamic buffer up until the ring buffer limit, and then start assigning instead of appending, starting with index 0. However, I don't think I can use an ECB to assign elements to a dynamic buffer. And, I can't immediately assign a deferred entity, since it will have Entity Index -1. Project details: I need to create entities of a particular archetype and keep track of the order in which I create them. Once I create enough entities, I need to delete the oldest one to make room for a new one. This is one reason why I need to keep track of the order, but there are other project-specific reasons to know the order, too. New plan: - Job 0: Defer entity creation. Also add `NewlyCreatedTag` and `DynamicBufferIndex` - Playback ECB from Job 0. - Job 1: Iterate through `NewlyCreatedTag` entities, wrapping each in a dynamic buffer element and assigning it to the dynamic buffer according to its `DynamicBufferIndex` component. Remove `NewlyCreatedTag`. Elaboration of new plan: I need a reference to the oldest entity so I can destroy it, to destroy its PhysicsCollider and other no-longer-needed data in the world. I will assign the new entities to the dynamic buffer after the playback, where the entity references will be available, while still aggregating all the deferred entity destructions, entity creations, and component additions into one sync point. However, since I still don't explicitly have the new entity references from the playback, I will add a `NewlyCreatedTag` and a `DynamicBufferIndex` component to the new entities (recorded in Job 0), so I can recover the new entity references after the playback. I invite thoughts and advice.