Database Replication

Copying data from a primary database to one or more replicas so the system survives failures, can serve reads from replicas and keeps data near users. It is the basis of high availability and many disaster recovery designs.

Synchronous replication waits for a replica to confirm a write before committing, which protects against data loss but adds latency. Asynchronous replication commits immediately and ships changes afterwards, which is faster but can lose recent writes if the primary fails.

Physical replication ships the storage-level log and produces an identical copy, which suits standbys and failover. Logical replication sends row-level changes, so it can replicate selected tables, cross major versions and feed other systems. PostgreSQL documents both.

A design in which several nodes accept writes, such as Galera Cluster, pgEdge Spock, EDB Postgres Distributed and CouchDB. It improves write availability but requires conflict handling.

No. Replicas copy deletions and corruption too, so you still need backups and point-in-time recovery, for example with pgBackRest or Barman for PostgreSQL.

Replication keeps a database copy in sync, while CDC streams changes from a database log to other systems such as Kafka or a warehouse. Many tools do both. See the Change Data Capture Platforms page.

Links and release facts were checked on 31 October 2026 from GitHub. The MySQL documentation and galeracluster.com returned 403 to automated checks. Orchestrator is archived, and repmgr and pg_auto_failover have not had a release in over a year, as their cards note. Descriptions follow each project's own pages and are not rankings.

See the Database Sharding page for sharding middleware such as Vitess, Citus and ShardingSphere, built-in sharding in MongoDB and distributed SQL systems, shard key design and case studies.

See the Database Transactions page for isolation level documentation, MVCC, distributed transactions, sagas, Jepsen correctness testing and key papers.

See the Database Backup and Recovery page for native backup tools, point-in-time recovery, cloud backup services, Kubernetes backup with Velero and disaster recovery planning.

See the Database Security page for access control, encryption, auditing, masking, SQL injection prevention, cloud database security features and hardening guides.