mybatis分表策略shard

Dear 丶 2022-06-17 00:27 283阅读 0赞

分表，通常在数据量大的情况下进行，当然应该先对项目的数据量进行数量级的预估，以根据不同的需求进行采用不同的分表策略。

(shard在mybatis中的配置就不多聊了，直接搜"mybatis分表"会有很多资料，大多类似)

shard原理，相当于一个过滤器，在执行sql语句之前对表名进行处理。

shard\_config.xml的配置：

<?xml version="1.0" encoding="UTF-8"?>  
    <!DOCTYPE shardingConfig PUBLIC "-//shardbatis.googlecode.com//DTD Shardbatis 2.0//EN" 
    "http://shardbatis.googlecode.com/dtd/shardbatis-config.dtd">  
    <shardingConfig>
           <parseList>  
                    <value>com.hello.IDao.AuthLogMapper.insert</value>
                    <value>com.hello.IDao.IdcardCacheMapper.insert</value>
           </parseList>  
          
            <strategy tableName ="auth_log" strategyClass = "com.hello.strategy.ShardStrategyImpl"/> 
            <strategy tableName ="idcard_cache" strategyClass = "com.hello.strategy.ShardStrategyImpl"/>
    </shardingConfig>

以上配置中，auth\_log和idcard\_cache两个表都采用了ShardStrategyImpl进行分表策略的处理，auth\_log采用根据日期进行分表，而idcard\_cache采用根据idcard的哈希值分为20个表。像参数中有hashmap之类的可以根据不同的sql进行不同的分表处理。大体思路是：根据表名，参数类别，参数值的不同采用不同的分表策略。

public class ShardStrategyImpl implements ShardStrategy {
    	private static int idCardTbName = 20;
    	private static SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd");
    	@Override
    	public String getTargetTableName(String tableName, Object arg1, String arg2) {
    		if("auth_log".equals(tableName)){
    			//认证记录分表策略
    			Class<?> cla = arg1.getClass();
    			if(cla == HashMap.class){
    				HashMap<String,Object> hs = (HashMap<String,Object>)arg1;
    				String date= hs.get("date").toString();
    				String sTableName = tableName + "_" + date;
    				return sTableName;
    			}
    			String sTableName = tableName + "_" + sdf.format(new Date());
    			return sTableName;
    		}else if("idcard_cache".equals(tableName)){
    			//信息表分表策略
    			Class<?> cla = arg1.getClass();
    			if(cla == HashMap.class){
    				HashMap<String,Object> hs = (HashMap<String,Object>)arg1;
    				String idCard= hs.get("idCard").toString();
    				int s = idCard.hashCode();
    				String sTableName = tableName + "_" + Math.abs(s)%idCardTbName;
    				System.out.println(sTableName);
    				return sTableName;
    			}
    			if(cla == IdcardCache.class){
    				IdcardCache ic = (IdcardCache)arg1;
    				String idCard= ic.getCardNo();
    				int s = idCard.hashCode();
    				String sTableName = tableName + "_" + Math.abs(s)%idCardTbName;
    				System.out.println(sTableName);
    				return sTableName;
    			}
    			return tableName;
    		}
    		return tableName;
    	}
    }