mysql换到mongodb主键问题_记一次从mongodb到mysql的数据迁移

需要对mongodb进行分页查询，但是分页查询效率很慢，mongdb中存在主键增长，故取出最大id，定义pageSize，当前传入的id如果加上pageSize小于最大值时，userId+=pageSize，简单代码如下

IntegerpageSize =200;

final LongmaxId =17202814L;

log.info("插入开始时间为{}", LocalDateTime.now());

boolean flag =true;

int pageNo =0;

while (flag) {

try {

if (userId >maxId) {

flag =false;

}

long startTime = System.currentTimeMillis();

//log.info("当前pageNo为{}", pageNo);

//int start = pageNo * pageSize;

Query query =new Query(Criteria.where("_id").gt(userId).lte(userId +pageSize));

userId +=pageSize;

//查出分页用户

List xpUsers =mongoTemplate.find(query, XpUser.class);

long endTime = System.currentTimeMillis();

log.info("从mongodb中查出数据时间{}", (endTime - startTime));

/*if (xpUsers.size() != 0) {*/

if(xpUsers.size()==0){

continue;

}

transferData(xpUsers, pageSize * (pageNo +1));

pageNo++;

startTime = System.currentTimeMillis();

log.info("封装插入mysql数据总时间{}", (startTime - endTime));

if (maxId - userId

//最后一条数据

pageSize = Math.toIntExact(maxId - userId);

if(pageSize <=0){

flag =false;

}

}

}catch (Exception e) {

flag =false;

log.error("插入出错,pageNo为{}", pageNo, e);

}

}

log.info("插入结束时间为{}", LocalDateTime.now());