![]() ![]() This method of data replication is sometimes referred to as transactional replication. The subscriber applies the data in the same order as the publisher so that transactional consistency is guaranteed for publications within a single subscription. The Aurora storage engine writes data to six copies in parallel spread across three Availability Zones. Once that is done, the changes on the publisher are sent to the subscriber as they occur in real-time. Aurora PostgreSQL uses a unique mechanism for replication in comparison to the community PostgreSQL to optimize over and above the decoupled storage layer. Logical replication of a table typically starts with taking a snapshot of the data on the publisher database and copying that to the subscriber. Subscribers pull data from the publications they subscribe to and may subsequently re-publish data to allow cascading replication or more complex configurations. In the next step, you need to modify the configuration file nf to allow replication (please refer to the PostgreSQL documentation for individual configuration): host all repuser 0.0.0.0/0 md5 Allow logical replication in nf. ![]() Logical replication uses a publish and subscribe model with one or more subscribers subscribing to one or more publications on a publisher node. For the MySQL, MariaDB, PostgreSQL, Oracle, and SQL Server database engines, Amazon RDS creates a second DB instance using a snapshot of the source DB instance. If the process is for any reason delayed, replication lags. Data changes at the source instance stream to Read Replica using streaming replication. Logical replication allows fine-grained control over both data replication and security. With AWS, you need to grant rdsreplication to the user instead. To create a read replica in the same AWS Region as the source instance, RDS PostgreSQL uses Postgres native streaming replication. PostgreSQL supports both mechanisms concurrently, see Chapter 27. An Aurora DB cluster can include up to 15 Aurora Replicas located throughout the Availability Zones of the Aurora DB cluster's AWS Region. ![]() We use the term logical in contrast to physical replication, which uses exact block addresses and byte-by-byte replication. An Aurora Replica is an independent endpoint in an Aurora DB cluster, best used for scaling read operations and increasing availability. Logical replication is a method of replicating data objects and their changes, based upon their replication identity (usually a primary key). ![]()
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