Databases
Read Replica
A copy of your database that stays in sync with the primary and serves read queries, spreading load and adding redundancy.
A read replica is a live copy of your primary database that continuously receives its changes. You point read-heavy traffic, reports, dashboards, product listings, at the replica, freeing the primary to handle writes. It's the standard first move when a single database instance starts straining under read load, and it doubles as a warm standby if the primary fails.
Most managed database services make replicas a checkbox. Vultr, for instance, prices managed databases by size and number of replica nodes, so adding read capacity or high availability is a config change rather than a project. The replica lags the primary by a small, usually sub-second, delay as changes propagate.
That replication lag is the thing to design around. A user who writes data and immediately reads it back from a replica might see stale results for a moment. For most read paths that's fine. For read-after-write flows, route those specific reads to the primary.