Comment Filter

Overview

With the comment filter it is possible to define comments that are injected before the actual statements. These comments appear as sql comments when they are received by the server.

[MyComment]
type=filter
module=comment
inject="Comment to be injected"

[MyService]
type=service
router=readwritesplit
servers=server1
user=myuser
password=mypasswd
filters=MyComment

Filter Parameters

The Comment filter requires one mandatory parameter to be defined.

inject

A parameter that contains the comment injected before the statements. There is also defined variable $IP that can be used to comment the IP address of the client in the injected comment. Variables must be written in all caps.

Examples

Example 1 - Inject IP address of the connected client into statements

as comment.

The following configuration adds the IP address of the client to the comment.

[IPComment]
type=filter
module=comment
inject="IP=$IP"

[MyService]
type=service
router=readwritesplit
servers=server1
user=myuser
password=mypasswd
filters=IPComment

In this example when MaxScale receives statement like:

 SELECT user FROM people;

It would look like

/* IP=::ffff:127.0.0.1 */SELECT user FROM people;

when received by server.