-
+
High Availability, Load Balancing, and Replication
- Trigger-Based Master-Slave Replication
+ Trigger-Based Master-Standby Replication
- A master-slave replication setup sends all data modification
+ A master-standby replication setup sends all data modification
queries to the master server. The master server asynchronously
- sends data changes to the slave server. The slave can answer
+ sends data changes to the standby server. The standby can answer
read-only queries while the master server is running. The
- slave server is ideal for data warehouse queries.
+ standby server is ideal for data warehouse queries.
Slony-I> is an example of this type of replication, with per-table
- granularity, and support for multiple slaves. Because it
- updates the slave server asynchronously (in batches), there is
+ granularity, and support for multiple standby servers. Because it
+ updates the standby server asynchronously (in batches), there is
possible data loss during fail over.
this is unacceptable, either the middleware or the application
must query such values from a single server and then use those
values in write queries. Another option is to use this replication
- option with a traditional master-slave setup, i.e. data modification
+ option with a traditional master-standby setup, i.e. data modification
queries are sent only to the master and are propagated to the
- slaves via master-slave replication, not by the replication
+ standby servers via master-standby replication, not by the replication
middleware. Care must also be taken that all
transactions either commit or abort on all servers, perhaps
using two-phase commit (
replication is best for mostly read workloads, though its big
advantage is that any server can accept write requests —
there is no need to partition workloads between master and
- slave servers, and because the data changes are sent from one
+ standby servers, and because the data changes are sent from one
server to another, there is no problem with non-deterministic
functions like random()>.
Shared Disk Failover
File System Replication
Hot/Warm Standby Using PITR
- Trigger-Based Master-Slave Replication
+ Trigger-Based Master-Standby Replication
Statement-Based Replication Middleware
Asynchronous Multimaster Replication
Synchronous Multimaster Replication
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- Slaves accept read-only queries
+ Standby accept read-only queries
Hot only
partitioned by offices, e.g., London and Paris, with a server
in each office. If queries combining London and Paris data
are necessary, an application can query both servers, or
- master/slave replication can be used to keep a read-only copy
+ master/standby replication can be used to keep a read-only copy
of the other office's data on each server.