Transactielog

Transactielog is a record-keeping mechanism used by information systems to chronicle executed transactions. It serves as the authoritative source for durability, recovery, and auditing, capturing the sequence of changes applied to a data store and related systems. In many database and distributed architectures, the transactielog is append-only: new entries are appended as transactions occur, and older entries are never modified. This design supports crash recovery, point-in-time restores, and replication to standby nodes.

Entries typically include a transaction identifier, a timestamp, the operation type (such as insert, update, delete), the affected data identifiers, and a payload or delta describing the changes. Depending on the system, the log may also record the transaction's outcome, commit or abort status, and metadata such as user or source. Some implementations separate metadata from data payloads to optimize storage and retrieval.

Common variants include a local transaction log within a single database instance and a global or distributed transaction log used to coordinate transactions across multiple services. In database systems, write-ahead logging and redo logs serve similar purposes by ensuring changes are durably recorded before they affect in-memory structures. In event-sourced architectures, the transactielog functions as the source of truth from which current state is built by replaying events.

Security and integrity measures are important, including cryptographic hashes, signatures, and tamper-evident chaining. Proper management of log retention, rotation, and access control is essential for compliance and performance. Typical use cases include crash recovery, replication to replicas, auditing for regulatory requirements, and debugging by replaying transactions to verify behavior.