DolphinDB数据库同步：MySQL/PostgreSQL到DolphinDB

摘要

本文深入讲解DolphinDB数据库同步技术。从同步方案设计到数据迁移，从增量同步到数据转换，从定时任务到实时同步，全面介绍数据库同步的核心方法。通过丰富的代码示例，帮助读者掌握数据同步的核心技能。

一、数据库同步概述

1.1 同步场景

1.2 同步方案

二、MySQL数据同步

2.1 连接MySQL

//加载MySQL插件 loadPlugin("mysql")//连接MySQL conn=mysql::connect("localhost",3306,"root","password","test_db")//测试连接 mysql::query(conn,"SELECT 1")

2.2 全量同步

//全量同步MySQL表到DolphinDB//1.查询MySQL数据 mysqlData=mysql::query(conn,"SELECT * FROM sensor_data")//2.创建DolphinDB表 db=database("dfs://mysql_sync_db",VALUE,1..100)schema=table(1:0,`device_id`timestamp`temperature`humidity,[INT,TIMESTAMP,DOUBLE,DOUBLE])db.createPartitionedTable(schema,`sensor_data,`device_id)//3.写入数据 loadTable("dfs://mysql_sync_db","sensor_data").append!(mysqlData)//4.验证 select count(*)fromloadTable("dfs://mysql_sync_db","sensor_data")

2.3 增量同步

//增量同步：基于时间戳//记录最后同步时间 share table(1:0,`table_name`last_sync_time,[STRING,TIMESTAMP])assync_status//增量同步函数defincrementalSync(conn,tableName){//获取最后同步时间 lastTime=execlast_sync_timefromsync_status where table_name=tableNameif(lastTime.size()==0){lastTime=1970.01.01//首次同步}//查询增量数据 sql="SELECT * FROM "+tableName+" WHERE update_time > '"+lastTime+"'"newData=mysql::query(conn,sql)//写入DolphinDBif(newData.rows()>0){loadTable("dfs://mysql_sync_db",tableName).append!(newData)//更新同步状态 maxTime=execmax(update_time)fromnewData update sync_statussetlast_sync_time=maxTime where table_name=tableName}returnnewData.rows()}//定时执行 scheduleJob("mysql_incremental","MySQL增量同步",def(){incrementalSync(conn,"sensor_data")},00:05,2024.01.01,2030.12.31,'D')

三、PostgreSQL数据同步

3.1 连接PostgreSQL

//加载PostgreSQL插件 loadPlugin("postgresql")//连接PostgreSQL conn=postgresql::connect("localhost",5432,"postgres","password","test_db")//测试连接 postgresql::query(conn,"SELECT 1")

3.2 全量同步

//全量同步PostgreSQL表 pgData=postgresql::query(conn,"SELECT * FROM sensor_data")//写入DolphinDB loadTable("dfs://pg_sync_db","sensor_data").append!(pgData)

3.3 增量同步

//PostgreSQL增量同步defpgIncrementalSync(conn,tableName){lastTime=execlast_sync_timefromsync_status where table_name=tableName sql="SELECT * FROM "+tableName+" WHERE updated_at > '"+lastTime+"'"newData=postgresql::query(conn,sql)if(newData.rows()>0){loadTable("dfs://pg_sync_db",tableName).append!(newData)maxTime=execmax(updated_at)fromnewData update sync_statussetlast_sync_time=maxTime where table_name=tableName}returnnewData.rows()}

四、数据转换

4.1 类型映射

//MySQL/PostgreSQL->DolphinDB 类型映射//MySQL类型映射defmysqlTypeToDolphinDB(mysqlType){typeMap=dict(STRING,STRING,[["INT","INT"],["BIGINT","LONG"],["FLOAT","FLOAT"],["DOUBLE","DOUBLE"],["VARCHAR","STRING"],["DATETIME","DATETIME"],["TIMESTAMP","TIMESTAMP"]])returntypeMap[mysqlType]}

4.2 数据清洗

//数据清洗函数defcleanData(data){//处理NULL值 cleaned=select device_id,timestamp,iif(temperatureisnull,avg(temperature),temperature)astemperature,iif(humidityisnull,avg(humidity),humidity)ashumidityfromdatareturncleaned}

4.3 数据验证

//数据验证defvalidateData(data){//检查必填字段if(sum(isNull(data.device_id))>0){throw"device_id存在空值"}//检查数据范围if(sum(data.temperature<-40ordata.temperature>100)>0){throw"temperature超出范围"}returntrue}

五、实时同步

5.1 Binlog同步（MySQL）

//MySQL Binlog实时同步//需要开启MySQL Binlog//配置Binlog监听 binlogConfig=dict(STRING,ANY,[["host","localhost"],["port",3306],["user","root"],["password","password"],["serverId",1]])//启动Binlog监听//mysql::startBinlogListener(binlogConfig,handler)

5.2 CDC同步

//使用Debezium CDC//1.部署Debezium连接器//2.捕获变更事件//3.推送到Kafka//4.DolphinDB消费Kafka

六、同步监控

6.1 同步状态表

//创建同步状态表 share table(1:0,`source_table`target_table`sync_time`sync_count`status`error_msg,[STRING,STRING,TIMESTAMP,LONG,STRING,STRING])assync_log//记录同步日志deflogSync(sourceTable,targetTable,count,status,errorMsg=""){insert into sync_log values(sourceTable,targetTable,now(),count,status,errorMsg)}

6.2 监控函数

//同步监控defmonitorSync(){print("=== 数据同步监控 ===")//最近同步记录 recentSyncs=select top10*fromsync_log order by sync_time descprint(recentSyncs)//失败记录 failures=select count(*)ascntfromsync_log where status="FAILED"print("失败次数: "+string(failures.cnt))}monitorSync()

七、实战案例

7.1 MySQL到DolphinDB完整同步

//==========MySQL到DolphinDB完整同步==========//1.加载插件 loadPlugin("mysql")//2.连接MySQL mysqlConn=mysql::connect("localhost",3306,"root","password","iot_db")//3.创建DolphinDB表 db=database("dfs://sync_db",VALUE,1..1000)schema=table(1:0,`device_id`timestamp`temperature`humidity`pressure,[INT,TIMESTAMP,DOUBLE,DOUBLE,DOUBLE])db.createPartitionedTable(schema,`sensor_data,`device_id)//4.全量同步deffullSync(conn,tableName){print("开始全量同步: "+tableName)data=mysql::query(conn,"SELECT * FROM "+tableName)loadTable("dfs://sync_db",tableName).append!(data)print("同步完成: "+string(data.rows())+" 条")logSync(tableName,tableName,data.rows(),"SUCCESS")}//5.增量同步defincrementalSync(conn,tableName){print("开始增量同步: "+tableName)lastTime=execmax(timestamp)fromloadTable("dfs://sync_db",tableName)sql="SELECT * FROM "+tableName+" WHERE timestamp > '"+string(lastTime)+"'"data=mysql::query(conn,sql)if(data.rows()>0){loadTable("dfs://sync_db",tableName).append!(data)print("增量同步: "+string(data.rows())+" 条")}logSync(tableName,tableName,data.rows(),"SUCCESS")}//6.执行同步 fullSync(mysqlConn,"sensor_data")//7.定时增量同步 scheduleJob("incremental_sync","增量同步",def(){incrementalSync(mysqlConn,"sensor_data")},00:10,2024.01.01,2030.12.31,'D')print("MySQL到DolphinDB同步系统启动完成")

八、总结

本文详细介绍了DolphinDB数据库同步：

1. 同步方案：全量同步、增量同步、实时同步
2. MySQL同步：连接、全量、增量
3. PostgreSQL同步：连接、全量、增量
4. 数据转换：类型映射、数据清洗、数据验证
5. 实时同步：Binlog、CDC
6. 同步监控：状态表、监控函数

思考题：

1. 如何选择合适的同步方案？
2. 如何保证数据同步的一致性？
3. 如何处理同步失败问题？

参考资料

• DolphinDB MySQL插件
• DolphinDB PostgreSQL插件