MySQL Router 8.4
To enable read-write splitting, the following
router options must be enabled:
access_mode: must be set
to auto.
It is possible to define read_write and
read_only
access_mode values per
session, only. See
Per-Session Configuration.
connection_sharing: must
be set to 1.
protocol: must be set to
classic.
destinations: must be
set to a metadata-cache URL with the role
set to PRIMARY_AND_SECONDARY.
Read-write splitting configuration can be defined per session, using one of the following:
ROUTER SET
optionName='value'
query_attributes
router.
optionName
value
The following are the possible
optionNames
access_mode set to one of the following
values:
read_write: all session traffic is
sent to a read_write server.
read_only: all session traffic is
sent to a read_only server.
auto: the server is selected based
on the type of transaction, reads are targetted to
read_only servers, writes to read_write servers.
wait_for_my_writes [ 0 | 1 ]: If
enabled, 1, read-only queries wait for
the last written transaction of the session.
wait_for_my_writes_timeout [ 0 | 4294967295
]: Maximum time in seconds to wait for a
read_only destination to apply the written transaction,
before falling back to a read_write destination. Default
is 1.
Session variables are reset to their initial values if the
client sends a change_user or
reset_connection.
For example:
SQL> ROUTER SET access_mode='read_write'
SQL> query_attribute router.access_mode read_write
When MySQL Router is bootstrapped, the default configuration is created with the following values:
[DEFAULT] max_idle_server_connections=64 [routing:read_write_split] bind_port=6450 destinations=metadata-cache://mycluster/?role=PRIMARY_AND_SECONDARY routing_strategy=round-robin access_mode=auto protocol=classic connection_sharing=1
To disable this configuration, you must bootstrap with
--disable-rw-split.