##Sharding-JDBC - A JDBC driver for shard databases and tables

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Overview

Sharding-JDBC is a JDBC extension, provides distributed features such as sharding, read/write splitting and BASE transaction.

Features

1. Sharding

• Aggregation functions, group by, order by and limit SQL supported in distributed database.
• Join (inner/outer) query supported.
• Sharding operator =, BETWEEN and IN supported.
• Sharding algorithm customization supported.
• Hint supported.

2. Read/Write Splitting

• Same transaction data concurrency guarantee.
• Hint supported.

3. BASE Transaction

• Best efforts delivery transaction.
• Try confirm cancel transaction (TBD).

4. Compatibility

• ORM self-adapting. JPA, Hibernate, Mybatis, Spring JDBC Template or JDBC supported.
• Connection-pool self-adapting. DBCP, C3P0, BoneCP, Druid supported.
• Any Database supported theoretically. MySQL support only, will support Oracle, SQLServer, DB2 and PostgreSQL in future.

5. Configuration

• Java config
• Spring namespace
• YAML
• Inline expression

---

Architecture

Roadmap

Quick Start

Add maven dependency

<!-- import sharding-jdbc core -->
<dependency>
    <groupId>com.dangdang</groupId>
    <artifactId>sharding-jdbc-core</artifactId>
    <version>${latest.release.version}</version>
</dependency>

<!-- import other module if need -->

Rule configuration

ShardingRule shardingRule = ShardingRule.builder()
        .dataSourceRule(dataSourceRule)
        .tableRules(tableRuleList)
        .databaseShardingStrategy(new DatabaseShardingStrategy("sharding_column", new XXXShardingAlgorithm()))
        .tableShardingStrategy(new TableShardingStrategy("sharding_column", new XXXShardingAlgorithm())))
        .build();

Use raw JDBC API

DataSource dataSource = ShardingDataSourceFactory.createDataSource(shardingRule);
String sql = "SELECT i.* FROM t_order o JOIN t_order_item i ON o.order_id=i.order_id WHERE o.user_id=? AND o.order_id=?";
try (
        Connection conn = dataSource.getConnection();
        PreparedStatement preparedStatement = conn.prepareStatement(sql)) {
    preparedStatement.setInt(1, 10);
    preparedStatement.setInt(2, 1001);
    try (ResultSet rs = preparedStatement.executeQuery()) {
        while(rs.next()) {
            System.out.println(rs.getInt(1));
            System.out.println(rs.getInt(2));
        }
    }
}

Use spring namespace

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:rdb="http://www.dangdang.com/schema/ddframe/rdb" 
    xsi:schemaLocation="http://www.springframework.org/schema/beans 
                        http://www.springframework.org/schema/beans/spring-beans.xsd
                        http://www.springframework.org/schema/context 
                        http://www.springframework.org/schema/context/spring-context.xsd 
                        http://www.dangdang.com/schema/ddframe/rdb 
                        http://www.dangdang.com/schema/ddframe/rdb/rdb.xsd 
                        ">
    <context:property-placeholder location="classpath:conf/rdb/conf.properties" ignore-unresolvable="true"/>
    
    <bean id="dbtbl_0" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
        <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/dbtbl_0"/>
        <property name="username" value="root"/>
        <property name="password" value=""/>
    </bean>
    <bean id="dbtbl_1" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
        <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/dbtbl_1"/>
        <property name="username" value="root"/>
        <property name="password" value=""/>
    </bean>

    <rdb:strategy id="orderTableStrategy" sharding-columns="order_id" algorithm-expression="t_order_${order_id.longValue() % 4}"/>
    <rdb:strategy id="orderItemTableStrategy" sharding-columns="order_id" algorithm-expression="t_order_item_${order_id.longValue() % 4}"/>
    <rdb:data-source id="shardingDataSource">
        <rdb:sharding-rule data-sources="dbtbl_0,dbtbl_1">
            <rdb:table-rules>
                <rdb:table-rule logic-table="t_order" actual-tables="t_order_${0..3}" table-strategy="orderTableStrategy"/>
                <rdb:table-rule logic-table="t_order_item" actual-tables="t_order_item_${0..3}" table-strategy="orderItemTableStrategy"/>
            </rdb:table-rules>
            <rdb:default-database-strategy sharding-columns="user_id" algorithm-expression="dbtbl_${user_id.longValue() % 2 + 1}"/>
        </rdb:sharding-rule>
    </rdb:data-source>
</beans>