一、实测结果

1. 业务无感知，无死锁平滑

2. 线上800万数据以下 直接使用 alter 新增字段 300ms左右

3. 2000万数据，强制使用主键索引，每次查询50万数据 并插入新表 ，耗时 20s ，cpu 占45%

二、整体步骤

1. 创建新表 biz_table_new

2. 查询当前表first_max_id

   1. 确定当前同步数据量 37509688

3. 将数据同步至新表

   insert into biz_table_new(id,app_trade_no,trade_no,trade_sub_no,uid,account_type,relate_uid,relate_account_type,biz_type,biz_subtype,in_out,amount,balance_before,remark,extra,created_at,updated_at)
   select * from journal_2022 force index(PRIMARY)
   where  id>0 and id <=500000;select sleep(10);
   
   insert into biz_table_new(id,app_trade_no,trade_no,trade_sub_no,uid,account_type,relate_uid,relate_account_type,biz_type,biz_subtype,in_out,amount,balance_before,remark,extra,created_at,updated_at)
   select * from biz_table force index(PRIMARY)
   where  id>500000 and id <=1000000;select sleep(10);
           
   ....        
   

   1. 分批次查询，根据步长设置区间
   2. 每次执行完毕休眠10s

4. 验证数据一致性，截止到first_max_id的数据同步完成

   1. 根据max_id 验证历史数据是否一致

    select count(1) from biz_table where id<=37509688;
    select count(1) from biz_table_new where id<=37509688;
   

5. 评估1分钟后的increment值

   1. 查询当前max_id 如：37609688
   2. 当前业务，增长量 ，计算1分钟内的数据量，如：200000
   3. 得出预计的increment 值 如：37609688+200000=37809688

6. 执行表迁移

   1. 设置新表的Increment 值
   2. 重命名 biz_table 为 biz_table_bak
   3. 重命名 new_table 为 biz_table

    alter table biz_table_new  AUTO_INCREMENT =37809688;
    rename table biz_table to biz_table_bak;
    rename table biz_table_new to biz_table;
   

7. 同步新增数据量

   1. 计算biz_table_bak 的max_id 为 last_max_id 如 37808688
   2. 根据first_max_id () 、last_max_id 获取此区间数据，同步至新表

   insert into biz_table_new(id,app_trade_no,trade_no,trade_sub_no,uid,account_type,relate_uid,relate_account_type,biz_type,biz_subtype,in_out,amount,balance_before,remark,extra,created_at,updated_at)
   select * from biz_table force index(PRIMARY)
   where  id>37509688 and id <=37808688
   

8. 数据同步完毕

三、GO脚本分享

• 脚本

package utils

import "fmt"

const diffTmp = `
insert into %s(id,uid,account_type,balance,frozen,status,created_at,updated_at,app_alias)
     select *,"lailiao" as app_alias from %s_bak force index(PRIMARY)
     where  id>%d and id <=%d;select sleep(1);
`


func SyncDataV2(tmp string, oldTable, newTable string, step, minId, maxId int) string {
	if tmp == "" {
		tmp = defaultTmp
	}
	var sql string
	if minId < 0 {
		minId = 0
	}

	var nextId int
	for i := minId; i < maxId; i++ {
		nextId = minId + step
		if nextId > maxId {
			nextId = maxId
		}
		sql += fmt.Sprintf(tmp, newTable, oldTable, minId, nextId)
		minId = nextId
		if minId == maxId {
			break
		}
	}

	return sql
}

func SyncDiffData(tmp string, oldTable, newTable string, step, minId, maxId int) string {
	if tmp == "" {
		tmp = diffTmp
	}
	var sql string
	if minId < 0 {
		minId = 0
	}

	var nextId int
	for i := minId; i < maxId; i++ {
		nextId = minId + step
		if nextId > maxId {
			nextId = maxId
		}
		sql += fmt.Sprintf(tmp, newTable, oldTable, minId, nextId)
		minId = nextId
		if minId == maxId {
			break
		}
	}

	return sql
}

func VerifyData(oldTable, newTable string, max int) string {
	sql := fmt.Sprintf("select count(1) from %s where id<=%d;", oldTable, max)
	sql += fmt.Sprintf("select count(1) from %s where id<=%d;", newTable, max)
	return sql
}

func RenameTable(oldTable, newTable string, incrementId int) (sql string) {
	sql += fmt.Sprintf("alter table %s  AUTO_INCREMENT =%d;", newTable, incrementId)
	sql += fmt.Sprintf("rename table %s to %s;", oldTable, oldTable+"_bak")
	sql += fmt.Sprintf("rename table %s to %s;", newTable, oldTable)
	return sql
}

• 测试用例

func TestAccount(t *testing.T) {
	oldTable := "account"
	newTable := "account_new"

	//同步历史数据
	step := 100000
	min := 0
	max := 952317 //数据表max_id
	tmp := `
	insert into %s(id,uid,account_type,balance,frozen,status,created_at,updated_at,app_alias)
	select *,"xxx" as app_alias from %s force index(PRIMARY)
	where  id>%d and id <=%d;select sleep(10);
	`

  
	template := SyncDataV2(tmp, oldTable, newTable, step, min, max)
	t.Log(template)

	//验证数据一致性
	verify := VerifyData(oldTable, newTable, max)
	t.Log("Verify:\n",verify)

	//变更表名
	increment := max + 20000
	sql := RenameTable(oldTable, newTable, increment)
	t.Log("SyncData:\n",sql)


	//同步新增数据
	tmp = `
	insert into %s(id,uid,account_type,balance,frozen,status,created_at,updated_at,app_alias)
     select *,"lailiao" as app_alias from %s_bak force index(PRIMARY)
     where  id>%d and id <=%d;select sleep(1);
`
	template = SyncDiffData(tmp, oldTable, oldTable, step, max, increment)
	t.Log(template)
}