在项目中,我们经常遇到或用到分页,那么在大数据量(百万级以上)下,哪种分页算法效率最优呢?我们不妨用事实说话。
测试环境
硬件:CPU 酷睿双核T5750 内存:2G
软件:Windows server 2003 + Sql server 2005
OK,我们首先创建一数据库:data_Test,并在此数据库中创建一表:tb_TestTable
测试环境
硬件:CPU 酷睿双核T5750 内存:2G
软件:Windows server 2003 + Sql server 2005
OK,我们首先创建一数据库:data_Test,并在此数据库中创建一表:tb_TestTable
create database data_Test --创建数据库data_Test GO use data_Test GO create table tb_TestTable --创建表 ( id int identity(1,1) primary key, userName nvarchar(20) not null, userPWD nvarchar(20) not null, userEmail nvarchar(40) null ) GO
然后我们在数据表中插入2000000条数据:
--插入数据 set identity_insert tb_TestTable on declare @count int set @count=1 while @count<=2000000 begin insert into tb_TestTable(id,userName,userPWD,userEmail) values (@count,'admin','admin888','lli0077@yahoo.com.cn') set @count=@count+1 end set identity_insert tb_TestTable off
我首先写了五个常用存储过程:
1,利用select top 和select not in进行分页,具体代码如下:
create procedure proc_paged_with_notin --利用select top and select not in ( @pageIndex int, --页索引 @pageSize int --每页记录数 ) as begin set nocount on; declare @timediff datetime --耗时 declare @sql nvarchar(500) select @timediff=Getdate() set @sql='select top '+str(@pageSize)+' * from tb_TestTable where(ID not in(select top '
+str(@pageSize*@pageIndex)+' id from tb_TestTable order by ID ASC)) order by ID' execute(@sql) --因select top后不支技直接接参数,所以写成了字符串@sql select datediff(ms,@timediff,GetDate()) as 耗时 set nocount off; end
2,利用select top 和 select max(列键)
create procedure proc_paged_with_selectMax --利用select top and select max(列) ( @pageIndex int, --页索引 @pageSize int --页记录数 ) as begin set nocount on; declare @timediff datetime declare @sql nvarchar(500) select @timediff=Getdate() set @sql='select top '+str(@pageSize)
+' * From tb_TestTable where(ID>(select max(id) From (select top '
+str(@pageSize*@pageIndex)+' id From tb_TestTable order by ID) as TempTable)) order by ID' execute(@sql) select datediff(ms,@timediff,GetDate()) as 耗时 set nocount off; end
3,利用select top和中间变量--此方法因网上有人说效果最佳,所以贴出来一同测试
create procedure proc_paged_with_Midvar --利用ID>最大ID值和中间变量 ( @pageIndex int, @pageSize int ) as declare @count int declare @ID int declare @timediff datetime declare @sql nvarchar(500) begin set nocount on; select @count=0,@ID=0,@timediff=getdate() select @count=@count+1,@ID=case when @count<=@pageSize*@pageIndex then ID
else @ID end from tb_testTable order by id set @sql='select top '+str(@pageSize)+' * from tb_testTable where ID>'+str(@ID) execute(@sql) select datediff(ms,@timediff,getdate()) as 耗时 set nocount off; end
4,利用Row_number() 此方法为SQL server 2005中新的方法,利用Row_number()给数据行加上索引
create procedure proc_paged_with_Rownumber --利用SQL 2005中的Row_number() ( @pageIndex int, @pageSize int ) as declare @timediff datetime begin set nocount on; select @timediff=getdate() select * from (select *,Row_number() over(order by ID asc) as IDRank from tb_testTable)
as IDWithRowNumber where IDRank>@pageSize*@pageIndex and IDRank<@pageSize*(@pageIndex+1) select datediff(ms,@timediff,getdate()) as 耗时 set nocount off; end
5,利用临时表及Row_number
create procedure proc_CTE --利用临时表及Row_number ( @pageIndex int, --页索引 @pageSize int --页记录数 ) as set nocount on; declare @ctestr nvarchar(400) declare @strSql nvarchar(400) declare @datediff datetime begin select @datediff=GetDate() set @ctestr='with Table_CTE as (select ceiling((Row_number() over(order by ID ASC))/'+str(@pageSize)+')
as page_num,* from tb_TestTable)'; set @strSql=@ctestr+' select * From Table_CTE where page_num='+str(@pageIndex) end begin execute sp_executesql @strSql select datediff(ms,@datediff,GetDate()) set nocount off; end
OK,至此,存储过程创建完毕,我们分别在每页10条数据的情况下在第2页,第1000页,第10000页,第100000页,第199999页进行测试,耗时单位:ms 每页测试5次取其平均值
存过 | 第2页耗时 | 第1000页 | 第10000页 | 第100000页 | 第199999页 | 效率排行 |
1用not in | 0ms | 16ms | 47ms | 475ms | 953ms | 3 |
2用select max | 5ms | 16ms | 35ms | 325ms | 623ms | 1 |
3中间变量 | 966ms | 970ms | 960ms | 945ms | 933ms | 5 |
4row_number | 0ms | 0ms | 34ms | 365ms | 710ms | 2 |
5临时表 | 780ms | 796ms | 798ms | 780ms | 805ms | 4 |
测试结果显示:
输出窗口 | 复制 保存 |
select max >row_number>not in>临时表>中间变量
于是我对效率最高的select max方法用2分法进行了扩展,代码取自互联网,我修改了ASC排序时取不到值的BUG,测试结果:
存过 | 第2页耗时 | 第1000页 | 第10000页 | 第100000页 | 第199999页 | 效率排行 |
2分法 | 156ms | 156ms | 180ms | 470ms | 156ms | 1* |
从测试结果来看,使用2分法确实可以提高效率并使效率更为稳定,我又增加了第159999页的测试,用时仅296ms,效果相当的不错!
下面是2分法使用select max的代码,已相当完善。
--/*-----存储过程 分页处理 孙伟 2005-03-28创建 -------*/ --/*-----存储过程 分页处理 浪尘 2008-9-1修改----------*/ --/*----- 对数据进行了2分处理使查询前半部分数据与查询后半部分数据性能相同 -------*/ alter PROCEDURE proc_paged_2part_selectMax ( @tblName nvarchar(200), ----要显示的表或多个表的连接 @fldName nvarchar(500) = '*', ----要显示的字段列表 @pageSize int = 10, ----每页显示的记录个数 @page int = 1, ----要显示那一页的记录 @fldSort nvarchar(200) = null, ----排序字段列表或条件 @Sort bit = 0, ----排序方法,0为升序,1为降序(如果是多字段排列Sort指代最后一个
排序字段的排列顺序(最后一个排序字段不加排序标记)--程序传参如:' SortA Asc,SortB Desc,SortC ') @strCondition nvarchar(1000) = null, ----查询条件,不需where @ID nvarchar(150), ----主表的主键 @Dist bit = 0, ----是否添加查询字段的 DISTINCT 默认0不添加/1添加 @pageCount int = 1 output, ----查询结果分页后的总页数 @Counts int = 1 output ----查询到的记录数 ) AS SET NOCOUNT ON Declare @sqlTmp nvarchar(1000) ----存放动态生成的SQL语句 Declare @strTmp nvarchar(1000) ----存放取得查询结果总数的查询语句 Declare @strID nvarchar(1000) ----存放取得查询开头或结尾ID的查询语句 Declare @strSortType nvarchar(10) ----数据排序规则A Declare @strFSortType nvarchar(10) ----数据排序规则B Declare @SqlSelect nvarchar(50) ----对含有DISTINCT的查询进行SQL构造 Declare @SqlCounts nvarchar(50) ----对含有DISTINCT的总数查询进行SQL构造 declare @timediff datetime --耗时测试时间差 select @timediff=getdate() if @Dist = 0 begin set @SqlSelect = 'select ' set @SqlCounts = 'Count(*)' end else begin set @SqlSelect = 'select distinct ' set @SqlCounts = 'Count(DISTINCT '+@ID+')' end if @Sort=0 begin set @strFSortType=' ASC ' set @strSortType=' DESC ' end else begin set @strFSortType=' DESC ' set @strSortType=' ASC ' end --------生成查询语句-------- --此处@strTmp为取得查询结果数量的语句 if @strCondition is null or @strCondition='' --没有设置显示条件 begin set @sqlTmp = @fldName + ' From ' + @tblName set @strTmp = @SqlSelect+' @Counts='+@SqlCounts+' FROM '+@tblName set @strID = ' From ' + @tblName end else begin set @sqlTmp = + @fldName + 'From ' + @tblName + ' where (1>0) ' + @strCondition set @strTmp = @SqlSelect+' @Counts='+@SqlCounts+' FROM '+@tblName + ' where (1>0) '
+ @strCondition set @strID = ' From ' + @tblName + ' where (1>0) ' + @strCondition end ----取得查询结果总数量----- exec sp_executesql @strTmp,N'@Counts int out ',@Counts out declare @tmpCounts int if @Counts = 0 set @tmpCounts = 1 else set @tmpCounts = @Counts --取得分页总数 set @pageCount=(@tmpCounts+@pageSize-1)/@pageSize /**当前页大于总页数 取最后一页**/ if @page>@pageCount set @page=@pageCount --/*-----数据分页2分处理-------*/ declare @pageIndex int --总数/页大小 declare @lastcount int --总数%页大小 set @pageIndex = @tmpCounts/@pageSize set @lastcount = @tmpCounts%@pageSize if @lastcount > 0 set @pageIndex = @pageIndex + 1 else set @lastcount = @pagesize --//***显示分页 if @strCondition is null or @strCondition='' --没有设置显示条件 begin if @pageIndex<2 or @page<=@pageIndex / 2 + @pageIndex % 2 --前半部分数据处理 begin if @page=1 set @strTmp=@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName +' order by '+ @fldSort +' '+ @strFSortType else begin if @Sort=1 begin set @strTmp=@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName +' where '+@ID+' <(select min('+ @ID +') from ('+ @SqlSelect+' top '
+ CAST(@pageSize*(@page-1) as Varchar(20)) +' '+ @ID +' from '+@tblName +' order by '+ @fldSort +' '+ @strFSortType+') AS TBMinID)' +' order by '+ @fldSort +' '+ @strFSortType end else begin set @strTmp=@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName +' where '+@ID+' >(select max('+ @ID +') from ('+ @SqlSelect+' top '
+ CAST(@pageSize*(@page-1) as Varchar(20)) +' '+ @ID +' from '+@tblName +' order by '+ @fldSort +' '+ @strFSortType+') AS TBMinID)' +' order by '+ @fldSort +' '+ @strFSortType end end end else begin set @page = @pageIndex-@page+1 --后半部分数据处理 if @page <= 1 --最后一页数据显示 set @strTmp=@SqlSelect+' * from ('+@SqlSelect+' top '
+ CAST(@lastcount as VARCHAR(4))+' '+ @fldName+' from '+@tblName +' order by '+ @fldSort +' '+ @strSortType+') AS TempTB'+' order by '
+ @fldSort +' '+ @strFSortType else if @Sort=1 begin set @strTmp=@SqlSelect+' * from ('+@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '
+ @fldName+' from '+@tblName +' where '+@ID+' >(select max('+ @ID +') from('+ @SqlSelect+' top '
+ CAST(@pageSize*(@page-2)+@lastcount as Varchar(20)) +' '+ @ID +' from '+@tblName +' order by '+ @fldSort +' '+ @strSortType+') AS TBMaxID)' +' order by '+ @fldSort +' '+ @strSortType+') AS TempTB'+' order by '+ @fldSort +' '
+ @strFSortType end else begin set @strTmp=@SqlSelect+' * from ('+@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))
+' '+ @fldName+' from '+@tblName +' where '+@ID+' <(select min('+ @ID +') from('+ @SqlSelect+' top '
+ CAST(@pageSize*(@page-2)+@lastcount as Varchar(20)) +' '+ @ID +' from '+@tblName +' order by '+ @fldSort +' '+ @strSortType+') AS TBMaxID)' +' order by '+ @fldSort +' '+ @strSortType+') AS TempTB'+' order by '+ @fldSort +' '
+ @strFSortType end end end else --有查询条件 begin if @pageIndex<2 or @page<=@pageIndex / 2 + @pageIndex % 2 --前半部分数据处理 begin if @page=1 set @strTmp=@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName +' where 1=1 ' + @strCondition + ' order by '+ @fldSort +' '+ @strFSortType else if(@Sort=1) begin set @strTmp=@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName +' where '+@ID+' <(select min('+ @ID +') from ('+ @SqlSelect+' top '
+ CAST(@pageSize*(@page-1) as Varchar(20)) +' '+ @ID +' from '+@tblName +' where (1=1) ' + @strCondition +' order by '+ @fldSort +' '+ @strFSortType+') AS TBMinID)' +' '+ @strCondition +' order by '+ @fldSort +' '+ @strFSortType end else begin set @strTmp=@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName +' where '+@ID+' >(select max('+ @ID +') from ('+ @SqlSelect+' top '
+ CAST(@pageSize*(@page-1) as Varchar(20)) +' '+ @ID +' from '+@tblName +' where (1=1) ' + @strCondition +' order by '+ @fldSort +' '+ @strFSortType+') AS TBMinID)' +' '+ @strCondition +' order by '+ @fldSort +' '+ @strFSortType end end else begin set @page = @pageIndex-@page+1 --后半部分数据处理 if @page <= 1 --最后一页数据显示 set @strTmp=@SqlSelect+' * from ('+@SqlSelect+' top '
+ CAST(@lastcount as VARCHAR(4))+' '+ @fldName+' from '+@tblName +' where (1=1) '+ @strCondition +' order by '+ @fldSort +' '+ @strSortType+') AS TempTB'
+' order by '+ @fldSort +' '+ @strFSortType else if(@Sort=1) set @strTmp=@SqlSelect+' * from ('+@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '
+ @fldName+' from '+@tblName +' where '+@ID+' >(select max('+ @ID +') from('+ @SqlSelect+' top '+ CAST(@pageSize*(@page-2)
+@lastcount as Varchar(20)) +' '+ @ID +' from '+@tblName +' where (1=1) '+ @strCondition +' order by '+ @fldSort +' '+ @strSortType+') AS TBMaxID)' +' '+ @strCondition+' order by '+ @fldSort +' '+ @strSortType+') AS TempTB'+' order by '
+ @fldSort +' '+ @strFSortType else set @strTmp=@SqlSelect+' * from ('+@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '
+ @fldName+' from '+@tblName +' where '+@ID+' <(select min('+ @ID +') from('+ @SqlSelect+' top '
+ CAST(@pageSize*(@page-2)+@lastcount as Varchar(20)) +' '+ @ID +' from '+@tblName +' where (1=1) '+ @strCondition +' order by '+ @fldSort +' '+ @strSortType+') AS TBMaxID)' +' '+ @strCondition+' order by '+ @fldSort +' '+ @strSortType+') AS TempTB'+' order by '
+ @fldSort +' '+ @strFSortType end end ------返回查询结果----- exec sp_executesql @strTmp select datediff(ms,@timediff,getdate()) as 耗时 --print @strTmp SET NOCOUNT OFF GO
执行示例:
exec proc_paged_2part_selectMax
'tb_testTable',
'ID,userName,userPWD,userEmail',10,100000,'ID',0,null,'ID',0
原文地址:http://www.cnblogs.com/Joshualang/archive/2009/05/17/1458709.html
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