[Rapzid]

I use a generic subsystem modeled loosely after SQS and Golang River.

I have a visible_at field which indicates when the "message" will show up in checkout commands. When checked out or during a heartbeat from the worker this gets bumped up by a certain amount of time.

When a message is checked out, or re-checked out, a key(GUID) is generated and assigned. To delete the message this key must match.

A message can be checked out if it exists and the visible_at field is older or equal to NOW.

That's about it for semantics. Any further complexity, such as workflows and states, are modeled in higher level services.

If I felt it mattered for perf and was worth the effort I might model this in a more append-only fashion taking advantage of HOT updates and etc. Maybe partition the table by day and drop partitions older than longest supported process. Use the sparse index to indicate deleted.. Hard to say though with SSDs, HOT, and the new btree anti-split features..