Named Server Filter
Named Server Filter
Overview
The namedserverfilter is a filter module for MariaDB MaxScale which is able to route queries to servers based on regular expression matches.
Configuration
The configuration block for the Named Server filter requires the minimal filter options in its section within the maxscale.cnf file, stored in /etc/maxscale.cnf.
[NamedServerFilter] type=filter module=namedserverfilter match=some string server=server2 [MyService] type=service router=readwritesplit servers=server1,server2 user=myuser passwd=mypasswd filters=NamedServerFilter
Filter Options
The named server filter accepts the following options.
| Option | Description |
|---|---|
| ignorecase | Use case-insensitive matching |
| case | Use case-sensitive matching |
| extended | Use extended regular expression syntax (ERE) |
To use multiple filter options, list them in a comma-separated list.
options=case,extended
Note: The ignorecase and case options are mutually exclusive and only one of them should be used.
Filter Parameters
The named server filter requires two mandatory parameters to be defined.
match
A parameter that can be used to match text in the SQL statement which should be replaced.
match=TYPE[ ]*=
If the filter option ignorecase is used all regular expressions are evaluated with the option to ignore the case of the text, therefore a match option of select will match both type, TYPE and any form of the word with upper or lowercase characters.
server
This is the server where matching queries will be router. The server should be in use by the service which uses this filter.
server=server2
source
The optional source parameter defines an IP address that is used to match against the address from which the client connection to MariaDB MaxScale originates. Only sessions that originate from this IP address will have the match and replacement applied to them.
source=127.0.0.1
Since MaxScale 2.1 it's also possible to use % wildcards:
source=192.%.%.% source=192.168.%.% source=192.168.10.%
Please note that using source=% to match any IP it's not allowed.
user
The optional user parameter defines a user name that is used to match against the user from which the client connection to MariaDB MaxScale originates. Only sessions that are connected using this username will have the match and replacement applied to them.
user=john
Examples
Example 1 - Route queries targeting a specific table to a server
This will route all queries matching the regular expression *from *users to the server named server2. The filter will ignore character case in queries.
A query like SELECT * FROM users would be routed to server2 where as a query like SELECT * FROM accounts would be routed according to the normal rules of the router.
[NamedServerFilter] type=filter module=namedserverfilter match= *from *users options=ignorecase server=server2 [MyService] type=service router=readwritesplit servers=server1,server2 user=myuser passwd=mypasswd filters=NamedServerFilter
