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
1create database data_Test --创建数据库data_Test
2GO
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,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,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,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页耗时 第10000页耗时 第100000页耗时 第199999页耗时 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
--4临时表 780ms 796ms 798ms 780ms 805ms 4
--测试结果显示: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:
--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,getdate()) as 耗时
--print @strTmp
SET NOCOUNT OFF
GO
--执行示例:exec proc_paged_2part_selectMax 'tb_testtable','ID,userEmail',10,100000,'ID',null,0
--这种测试只在单机进行,并且没有在实际开发WEB项目中分页测试,测试项也比较单一,所以不够全面系统,但从其效率相比上,我们可以在数据库分页算法上进行有效的控制。
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