MySQL Router 8.4  /  ...  /  Configuration

3.5.1 Configuration

To enable read-write splitting, the following router options must be enabled:

Per-Session Configuration

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 and values:

  • 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:



To disable this configuration, you must bootstrap with --disable-rw-split.