The Connection Routing plugin performs connection-based routing, meaning it forwards packets to the server without inspecting them. This is a simplistic approach that provides high throughput. For additional general information about connection routing, see Section 1.3, “Connection Routing”.
A simple connection-based routing setup is shown below. These and additional options are documented under Section 4.3.3, “Configuration File Options”.
[logger] level = INFO [routing:secondary] bind_address = localhost bind_port = 7001 destinations = foo.example.org:3306,bar.example.org:3306,baz.example.org:3306 routing_strategy = round-robin [routing:primary] bind_address = localhost bind_port = 7002 destinations = foo.example.org:3306,bar.example.org:3306 routing_strategy = first-available
Here we use connection routing to round-robin MySQL connections to
three MySQL servers on port 7001 as defined by
routing_strategy. This example
also configures the first-available strategy
for two of the servers using port 7002. The first-available
strategy uses the first available server from the destinations
list. The number of MySQL instances assigned to each
destinations is up to you as
this is only an example. Router does not inspect the packets and
does not restrict connections based on assigned strategy or mode,
so it is up the application to determine where to send read and
write requests, which is either port 7001 or 7002 in our example.
Before MySQL Router 8.0, the now deprecated
mode option was used instead
option that was added in MySQL Router 8.0.
Assuming all three MySQL instances are running, next start MySQL Router by passing in the configuration file:
$> ./bin/mysqlrouter -config=/etc/mysqlrouter-config.conf
Now MySQL Router is listening to port's 7001 and 7002 and sends requests to the appropriate MySQL instances. For example:
$> ./bin/mysql --user=root --port 7001 --protocol=TCP
That will first connect to foo.example.org, and then bar.example.org next, then baz.example.org, and the fourth call goes back to foo.example.org. Instead, we configured port 7002 behavior differently:
$> ./bin/mysql --user=root --port 7002 --protocol=TCP
That first connects to foo.example.org, and additional requests
will continue connecting to foo.example.org until there is a
failure, at which point bar.example.org is now used. For
additional information about this behavior, see