Database

A single database that runs on a database instance.

Database instance

Database host machine, may contain multiple databases.

Logical replication

Replication at the level of operations; describes the operation, the arguments and data (e.g., an UPDATE is applied to row X setting column Y = Z).

Physical replication

Replication of the on-disk data structures after an operation has been applied.

Primary database (DB)

The customer’s database within a database instance that is being replicated. The source of truth for data for all copies of that database.

Write-ahead log (WAL)

Log used by a database to log database operations. Used for recovery replay or replication.