Module mz_catalog::durable::objects::state_update

This module contains various representations of a single catalog update and the logic necessary for converting between representations.

The general lifecycle of a single update when read from persist is as follows:

1. The update is stored in persist as a PersistStateUpdate.
2. After being read from persist the update is immediately converted into a StateUpdate<StateUpdateKindJson>, which models the update as a JSON.
3. The StateUpdateKindJson is converted into a protobuf message, proto::StateUpdateKind.
4. The update is then converted into a StateUpdate<StateUpdateKind>, which is a strongly typed Rust object.
5. Finally, the update is converted into an Option<memory::objects::StateUpdate>, and Some variants are given to the in-memory catalog. The in-memory catalog is only interested in a subset of catalog updates which is why the Option is necessary.

TLDR: PersistStateUpdate -> StateUpdate<StateUpdateKindJson> -> proto::StateUpdateKind -> StateUpdate<StateUpdateKind> -> Option<memory::objects::StateUpdate>

The process of writing a catalog update to persist is the exact opposite.

When running catalog protobuf upgrades/migrations we may need to take a detour and convert the StateUpdateKindJson to some proto::object_v{x}::StateUpdateKind before applying specific upgrades to get us to a valid proto::StateUpdateKind.

Structs

• StateUpdate
  A single update to the catalog state.
• StateUpdateKindJson
  Version of StateUpdateKind to allow reading/writing raw json from/to persist.

Enums

• StateUpdateKind
  The contents of a single state update.

Traits

• IntoStateUpdateKindJson
  Trait for objects that can be converted to/from a StateUpdateKindJson.
• TryIntoStateUpdateKind 🔒
  Trait for objects that can be converted to/from a StateUpdateKind.

Type Aliases

• PersistStateUpdate 🔒
  Version of StateUpdateKind that is stored directly in persist.