环境：mybatis+Oracle数据库 目标表里有240万条记录 目的：查询第60000页，25条记录

打印查询耗时

Long tiem1 = System.currentTimeMillis();

List<Mtsend_Info> mtsend_infos = infoMapper.selectByParam(sql);

System.out.print("耗时" + (System.currentTimeMillis() - tiem1) + "ms\n");

1.不用PageHelper，使用手动划分rownum 耗时831ms

02-0816:31:36[com.hengkang.app.mappers.Mtsend_InfoMapper.selectByParam-142][http-bio-8080-exec-3][45168] - ==> Preparing: select oidnew,to_char(putintime,'yyyy-mm-dd HH:mi:ss') timestr1,putintime,phone,msgcont,uc,channelid,pri,pknum,pktotal,state,feenum,submitmsgid,rptstate,rptinfo,to_char(rptrecvtime,'yyyy-mm-dd HH:mi:ss') timestr2,to_char(submittime,'yyyy-mm-dd HH:mi:ss') timestr3,chpri,linkid from(select a.*,rownum ro from HKSMGATEWAY_SMS.mtsend_info a where rownum <=1500000) where ro >1499975
02-0816:31:36[com.hengkang.app.mappers.Mtsend_InfoMapper.selectByParam-142][http-bio-8080-exec-3][45169] - ==> Parameters:
02-0816:31:36[com.hengkang.app.mappers.Mtsend_InfoMapper.selectByParam-142][http-bio-8080-exec-3][45998] - <== Total: 25
耗时831ms

2.使用PageHelper 耗时4477ms

Integet pageSize=25;
Integer start = (page - 1) * pageSize;
PageHelper.startPage(page, pageSize);

02-0816:28:44[com.hengkang.app.mappers.Mtsend_InfoMapper.selectByParam-142][http-bio-8080-exec-9][420872] - ==> Preparing: select * from ( select tmp_page.*, rownum row_id from ( select oidnew,to_char(putintime,'yyyy-mm-dd HH:mi:ss') timestr1,putintime,phone,msgcont,uc,channelid,pri,pknum,pktotal,state,feenum,submitmsgid,rptstate,rptinfo,to_char(rptrecvtime,'yyyy-mm-dd HH:mi:ss') timestr2,to_char(submittime,'yyyy-mm-dd HH:mi:ss') timestr3,chpri,linkid from HKSMGATEWAY_SMS.mtsend_info ) tmp_page where rownum <= ? ) where row_id > ?
02-0816:28:44[com.hengkang.app.mappers.Mtsend_InfoMapper.selectByParam-142][http-bio-8080-exec-9][420873] - ==> Parameters: 1500000(Integer), 1499975(Integer)
02-0816:28:48[com.hengkang.app.mappers.Mtsend_InfoMapper.selectByParam-142][http-bio-8080-exec-9][425087] - <== Total: 25
耗时4477ms