96af90628f
Added a note to the documentation of experimental modules that explains that the modules are distributed in a different package.
48 lines
1.6 KiB
Markdown
48 lines
1.6 KiB
Markdown
# Cat
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The `cat` router is a special router that concatenates result sets.
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*Note:* This module is a part of the experimental module package,
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`maxscale-experimental`.
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## Configuration
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The router has no special parameters. To use it, define a service with
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`router=cat` and add the servers you want to use.
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## Behavior
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The order the servers are defined in is the order in which the servers are
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queried. This means that the results are ordered based on the `servers`
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parameter of the service. The result will only be completed once all servers
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have executed this.
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All commands executed via this router will be executed on all servers. This
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means that an INSERT through the `cat` router will send it to all servers. In
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the case of commands that do not return resultsets, the response of the last
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server is sent to the client. This means that if one of the earlier servers
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returns a different result, the client will not see it.
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As the intended use-case of the router is to mainly reduce multiple result sets
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into one, it has no mechanisms to prevent writes from being executed on slave
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servers (which would cause data corruption or replication failure). Take great
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care when performing administrative operations though this router.
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If a connection to one of the servers is lost, the client connection will also
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be closed.
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## Example
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Here is a simple example service definition that uses the servers from the
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[Configuring Servers](../Tutorials/Configuring-Servers.md) tutorial and the
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credentials from the [MaxScale Tutorial](../Tutorials/MaxScale-Tutorial.md).
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```
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[concat-service]
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type=service
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router=cat
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servers=dbserv1,dbserv2,dbserv3
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user=maxscale
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password=maxscale_pw
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```
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