Tee Filter
Tee Filter
Overview
The tee filter is a "plumbing" fitting in the MariaDB MaxScale filter toolkit. It can be used in a filter pipeline of a service to make copies of requests from the client and send the copies to another service within MariaDB MaxScale.
Please Note: Starting with MaxScale 2.2.0, any client that connects to a
service which uses a tee filter will require a grant for the loopback address,
i.e. 127.0.0.1.
Configuration
The configuration block for the TEE filter requires the minimal filter parameters in its section within the MaxScale configuration file. The service to send the duplicates to must be defined.
[DataMartFilter] type=filter module=tee service=DataMart [Data Service] type=service router=readconnrouter servers=server1 user=myuser passwd=mypasswd filters=DataMartFilter
Filter Parameters
The tee filter requires a mandatory parameter to define the service to replicate statements to and accepts a number of optional parameters.
match
An optional parameter used to limit the queries that will be replicated by the tee filter. The parameter value is a PCRE2 regular expression that is used to match against the SQL text. Only SQL statements that match the text passed as the value of this parameter will be sent to the service defined in the filter section.
match=/insert.*into.*order*/
exclude
An optional parameter used to limit the queries that will be replicated by the tee filter. The parameter value is a PCRE2 regular expression that is used to match against the SQL text. Any SQL statements that match the text passed as the value of this parameter will be excluded from the replication stream.
exclude=/select.*from.*t1/
If both match and exclude parameters are defined, exclude takes
precedence.
options
The options parameter controls the regular expression options. The following options are accepted.
| 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
source
The optional source parameter defines an address that is used to match against the address from which the client connection to MariaDB MaxScale originates. Only sessions that originate from this address will be replicated.
source=127.0.0.1
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 are replicated.
user=john
Module commands
Read Module Commands documentation for details about module commands.
The tee filter supports the following module commands.
tee disable [FILTER]
This commmad disables a tee filter instance. A disabled tee filter will not send any queries to the target service.
tee enable [FILTER]
Enable a disabled tee filter. This resumes the sending of queries to the target service.
Examples
Example 1 - Replicate all inserts into the orders table
Assume an order processing system that has a table called orders. You also have another database server, the datamart server, that requires all inserts into orders to be replicated to it. Deletes and updates are not, however, required.
Set up a service in MariaDB MaxScale, called Orders, to communicate with the order processing system with the tee filter applied to it. Also set up a service to talk to the datamart server, using the DataMart service. The tee filter would have as it’s service entry the DataMart service, by adding a match parameter of "insert into orders" would then result in all requests being sent to the order processing system, and insert statements that include the orders table being additionally sent to the datamart server.
[Orders] type=service router=readconnroute servers=server1, server2, server3, server4 user=massi passwd=6628C50E07CCE1F0392EDEEB9D1203F3 filters=ReplicateOrders [ReplicateOrders] type=filter module=tee service=DataMart match=insert[ ]*into[ ]*orders [DataMart] type=service router=readconnroute servers=datamartserver user=massi passwd=6628C50E07CCE1F0392EDEEB9D1203F3 filters=QLA_DataMart [QLA_DataMart] type=filter module=qlafilter options=/var/log/DataMart/InsertsLog [Orders Listener] type=listener service=Orders protocol=MariaDBClient port=4011 [DataMart Listener] type=listener service=DataMart protocol=MariaDBClient port=4012
