DBLE Middleware Overview and schema.xml Configuration Guide

DBLE is an open‑source enterprise‑grade distributed middleware, nicknamed “MyCat Plus”, praised for its simplicity, stability, active community, and extensive support.

Official resources: website https://opensource.actionsky.com , GitHub project https://github.com/actiontech/dble , download page https://github.com/actiontech/dble/releases , and community group number 669663113.

The main configuration files are located in the conf directory. Key files include: server.xml: defines DBLE server parameters such as performance settings, scheduled tasks, ports, and user configurations. schema.xml: defines sharding rules, mapping between logical tables/schemas and physical data nodes, and specifies which sharding method each table uses. rule.xml: configures the actual sharding algorithms used by DBLE.

schema.xml is the most frequently edited file for configuring logical‑to‑physical database relationships. An example schema.xml is shown below, followed by a diagram illustrating the mapping.

<?xml version="1.0"?>
<!DOCTYPE dble:schema SYSTEM "schema.dtd">
<dble:schema xmlns:dble="http://dble.cloud/">
    <schema name="testdb">
        <table name="goods" primaryKey="ID" type="global" dataNode="dn1,dn2" />
        <table name="order" primaryKey="ID" dataNode="dn1,dn2" rule="sharding-by-date" />
    </schema>
    <!-- Sharding configuration -->
    <dataNode name="dn1" dataHost="dh1" database="db1"/>
    <dataNode name="dn2" dataHost="dh2" database="db2"/>
    <!-- Physical database configuration -->
    <dataHost name="dh1" maxCon="1000" minCon="10" balance="0" switchType="1" slaveThreshold="100">
        <heartbeat>show slave status</heartbeat>
        <writeHost host="MySQLA" url="172.16.1.1:3306" user="test" password="password"/>
    </dataHost>
    <dataHost name="dh2" maxCon="1000" minCon="10" balance="0" switchType="1" slaveThreshold="100">
        <heartbeat>show slave status</heartbeat>
        <writeHost host="MySQLB" url="172.16.1.2:3306" user="test" password="password">
            <readHost host="MySQLC" url="172.16.1.3:3306" user="test" password="password"/>
        </writeHost>
    </dataHost>
</dble:schema>

The example defines a schema testdb with two tables ( goods and order) assigned to data nodes dn1 and dn2. Data nodes reference physical hosts dh1 and dh2, each with connection details, heartbeat queries, and read/write host configurations.

Mastering the concepts in schema.xml enables effective DBLE configuration; for advanced usage and detailed options, refer to the official documentation.