What is semi sync replication?

What is semi sync replication?

Semisynchronous replication falls between asynchronous and fully synchronous replication. The source waits until at least one replica has received and logged the events (the required number of replicas is configurable), and then commits the transaction.

What is semi synchronous?

A semi-synchronous orbit is an orbit with a period equal to half the average rotational period of the body being orbited, and in the same direction as that body’s rotation. For Earth, a semi-synchronous orbit is considered a medium Earth orbit, with a period of just under 12 hours.

What is the difference between synchronous and asynchronous replication?

Most synchronous replication products write data to primary storage and the replica simultaneously. As such, the primary copy and the replica should always remain synchronized. In contrast, asynchronous replication products copy the data to the replica after the data is already written to the primary storage.

What is MySQL semi synchronous replication?

Semi-sync replication was introduced in MySQL 5.5. Its promise is that every transaction where the client has received a COMMIT acknowledgment would be replicated to a slave. It had a caveat though: while a client is waiting for this COMMIT acknowledgment, other clients could see the data of the committing transaction.

Is MySQL replication synchronous?

MySQL replication by default is asynchronous. The source writes events to its binary log and replicas request them when they are ready.

What is synchronous versus asynchronous?

The key difference between synchronous and asynchronous communication is synchronous communications are scheduled, real-time interactions by phone, video, or in-person. Asynchronous communication happens on your own time and doesn’t need scheduling.

What is PostgreSQL replication?

What Is PostgreSQL Replication? The process of copying data from a PostgreSQL database server to another server is called PostgreSQL Replication. The source database server is usually called the Master server, whereas the database server receiving the copied data is called the Replica server.

What is a synchronous replication?

Synchronous replication is the process of copying data over a storage area network, local area network or wide area network so there are multiple, current copies of the data. Synchronous replication is mainly used for high-end transactional applications that need instant failover if the primary node fails.

What is the semisynchronous replication plugin?

The semisynchronous replication plugin is actually two different plugins–one for the primary, and one for the replica. Shared libraries for both plugins are included with MariaDB. Although the plugins’ shared libraries distributed with MariaDB by default, the plugin is not actually installed by MariaDB by default prior to MariaDB 10.3.3.

What are the disadvantages of semisynchronous replication?

With semisynchronous replication, if the source crashes and a failover to a replica is carried out, the failed source should not be reused as the replication source, and should be discarded. It could have transactions that were not acknowledged by any replica, which were therefore not committed before the failover.

Does MySQL 8 support semisynchronous replication?

IF EXISTS Statements MySQL 8.0 Reference Manual / / In addition to the built-in asynchronous replication, MySQL 8.0 supports an interface to semisynchronous replication that is implemented by plugins. This section discusses what semisynchronous replication is and how it works.

What is semisynchronous replication in MariaDB?

Since the delay is based on the roundtrip time to the replica and back, this delay is minimized for servers in close proximity over fast networks. In MariaDB 10.3 and later, semisynchronous replication is built into the server, so it can be enabled immediately in those versions.