ReferenceGlossary
Read replica
A copy of a database that follows the primary's writes and answers read-only queries. It takes read load off the primary. Replication is usually asynchronous, so a replica can lag behind and return data that is a little old.
Data
In Quorum#
The Read replicas Research unlocks the Read Replica, which runs like a Database but answers only q-read. It lags 20 ms plus 2 ms for each write per second, and up to 15% of its reads come back stale; a Replication lag Incident makes the lag ten times larger. Read-your-writes routing sends reads that follow a write to the primary. A replica in another region also limits how much data you lose if the home region fails.
Read next#
Replication lag, Read-your-writes consistency, Eventual consistency, Synchronous replication