lastUpdated

lastupdated is a metadata attribute used in information systems to record the most recent time a resource was modified. It is typically represented as a timestamp and is used to support synchronization, auditing, and caching. In practice, the term appears in databases, content management systems, APIs, and file storage where keeping track of changes is important.

Common implementations store lastupdated in a dedicated column such as last_updated or updated_at. Data types include DATETIME, TIMESTAMP, or ISO 8601 strings; some systems store the value as milliseconds since the epoch. The field is usually updated automatically on insert and update via database triggers, ORM features, or application logic.

Format conventions emphasize using UTC to avoid time zone ambiguity. ISO 8601 is widely used (for example, 2025-12-07T12:34:56Z). In high-traffic systems, epoch or integer timestamps can be preferred for performance. It may be stored alongside a creation timestamp to distinguish creation from modification.

Usage includes enabling efficient caching with HTTP Last-Modified headers, supporting incremental data synchronization, and providing a basis for optimistic concurrency control when combined with version numbers or ETags. It does not convey what changed, only when.

Common considerations include clock synchronization, time zone handling, and ensuring updates are atomic to prevent stale values. In bulk operations, lastupdated should reflect the most recent change across affected items. Care should be taken to avoid inconsistent naming across systems to reduce confusion.

Best practices include using a consistently named updated_at field, indexing it for query performance, and using automated mechanisms to set and update the value. Documenting its semantics helps users interpret data correctly.