Which is the best replication solution for MySQL?
MySQL Replication is probably the most popular high availability solution for MySQL, and widely used by top web properties like Twitter and Facebook. Although easy to set up, ongoing maintenance like software upgrades, schema changes, topology changes, failover and recovery have always been tricky. At least until MySQL 5.6.
How does semi synchronous replication work in MySQL?
MySQL also supports semi-synchronous replication, where the master does not confirm transactions to the client until at least one slave has copied the change to its relay log, and flushed it to disk.
How is replication used in a web server?
Replication in this situation enables you to distribute the reads over the replicas, while still enabling your web servers to communicate with the source when a write is required. You can see a sample replication layout for this scenario in Figure 17.1, “Using Replication to Improve Performance During Scale-Out” .
When to use replication for scale-out in a website?
Because replication works from the distribution of one source to one or more replicas, using replication for scale-out works best in an environment where you have a high number of reads and low number of writes/updates. Most websites fit into this category, where users are browsing the website, reading articles, posts, or viewing products.
How does Azure database for MySQL high availability work?
In the event of failover, Azure Database for MySQL flexible server automatically fails over to the standby replica if high availability is enabled. The high availability setup monitors the primary server and bring it back online. Clients always connect to the primary database server.
Why is MySQL replication lag so bad?
Normally, IO_THREAD doesn’t cause large replication delays, because the IO_THREAD only reads the binary logs from the primary or source instance. However, network connectivity and network latency can affect the speed of the reads between the servers.
Why does MySQL failover from master to slave?
Slave can be arbitrarily behind master in reading or applying changes. If the master crashes, transactions that it has committed might not have been transmitted to any slave. Consequently, failover from master to slave in this case may result in failover to a server that is missing transactions relative to the master.