Backends

Stateful native operators (aggregates, joins, dedup, Top-N, and the rest) hold their state behind a state.backend.type-selected store:

• Memory — the default. Full raw keyed-state blobs, checkpointed whole.
• Paimon (experimental) — a persistent backend built on local Apache Paimon primary-key tables, with incremental checkpoints instead of whole-state snapshots.

Both backends run the same native operators and produce the same results — the backend only changes how state durably survives a checkpoint/restore, never query semantics. See each page for exactly which operators and shapes are covered.