Püsivälist

Püsivälist is a term used in Finnish information technology to describe a list data structure or collection whose contents are stored in non-volatile storage and thus persist beyond the lifetime of a single program instance. The concept contrasts with ephemeral lists that exist only in memory and disappear when the process ends or the system reboots.

Key characteristics of a püsivälist include persistence, ordered elements, and support for standard list operations such as adding, inserting, removing, and retrieving elements. In practice, a püsivälist is implemented by backing the in-memory sequence with a durable storage mechanism, which can be a database, a file, or another form of persistent storage. The exact implementation may influence performance, consistency guarantees, and how ordering is preserved.

Implementation approaches vary. A database-backed püsivälist often stores elements as records with an explicit position or sequence number to maintain order, while a file-based approach may serialize the entire list or use an append-only log. Some designs emphasize immutability and versioning, creating snapshots or maintaining an audit trail of changes to support historical queries.

Typical use cases include UI components that must remember user-generated lists across sessions, configuration or metadata lists that must survive restarts, and audit-friendly histories where every change is recorded. Important design considerations include the choice of serialization format, durability guarantees, concurrency controls, and how to handle partial failures during updates.

See also: persistent data structures, append-only storage, local storage equivalents, database-backed collections.