Okuzeka
Databases & SQL vocabulary · Backup, Replication and Scaling

Read replica

Meaning in databases & SQL, with examples

nounCommon term

In databases & SQL, read replica means: A copy of a database that receives changes from the main server and is used only for read queries, taking load off the primary.

In Turkish: okuma replikası, salt okunur kopya

How it is used

The term is popular on cloud platforms such as Amazon RDS. Reports and search pages read from replicas while writes go to the primary. Because replication is usually asynchronous, a replica may return slightly old data, which surprises users who just saved something.

Example sentences

  1. Point the reporting service at the read replica, not the primary.

  2. The user saw old data because the read replica was a few seconds behind.

Common collocations

  • add a read replica
  • replica lag
  • read from the replica
  • promote a replica
  • replicationKeeping copies of the same database on several servers by sending every change from one server to the others, for safety and to share the load.
  • failoverSwitching work from a failed primary database server to a standby or replica so that the application can keep running.
  • high availabilityDesigning a database system so that it keeps working with very little downtime, even if a server, disk or data center fails.
  • shardingSplitting one large dataset across several database servers, each holding a different part of the rows, so the system can grow beyond one machine.

This word in other fields

The same English word can have a different meaning in another field:

More terms: Backup, Replication and Scaling

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