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
create database data_Test --创建数据库data_Test 2
GO 3
use data_Test 4
GO 5
create table tb_TestTable --创建表 6
( 7
id int identity(1,1) primary key, 8
userName nvarchar(20) not null, 9
userPWD nvarchar(20) not null, 10
userEmail nvarchar(40) null 11
) 12
GO
然后我们在数据表中插入2000000条数据:
--插入数据 2
set identity_insert tb_TestTable on 3
declare @count int 4
set @count=1 5
while @count<=2000000 6
begin 7
insert into tb_TestTable(id,userName,userPWD,userEmail) values(@count,'admin','admin888','lli0077@yahoo.com.cn') 8
set @count=@count+1 9
end 10
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:
2,利用select top 和 select max(列键) 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 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 5,利用临时表及Row_number 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
create procedure proc_paged_with_notin --利用select top and select not in
2
(
3
@pageIndex int, --页索引
4
@pageSize int --每页记录数
5
)
6
as
7
begin
8
set nocount on;
9
declare @timediff datetime --耗时
10
declare @sql nvarchar(500)
11
select @timediff=Getdate()
12
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'
13
execute(@sql) --因select top后不支技直接接参数,所以写成了字符串@sql
14
select datediff(ms,@timediff,GetDate()) as 耗时
15
set nocount off;
16
end
create procedure proc_paged_with_selectMax --利用select top and select max(列)
2
(
3
@pageIndex int, --页索引
4
@pageSize int --页记录数
5
)
6
as
7
begin
8
set nocount on;
9
declare @timediff datetime
10
declare @sql nvarchar(500)
11
select @timediff=Getdate()
12
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'
13
execute(@sql)
14
select datediff(ms,@timediff,GetDate()) as 耗时
15
set nocount off;
16
end
create procedure proc_paged_with_Midvar --利用ID>最大ID值和中间变量
2
(
3
@pageIndex int,
4
@pageSize int
5
)
6
as
7
declare @count int
8
declare @ID int
9
declare @timediff datetime
10
declare @sql nvarchar(500)
11
begin
12
set nocount on;
13
select @count=0,@ID=0,@timediff=getdate()
14
select @count=@count+1,@ID=case when @count<=@pageSize*@pageIndex then ID else @ID end from tb_testTable order by id
15
set @sql='select top '+str(@pageSize)+' * from tb_testTable where ID>'+str(@ID)
16
execute(@sql)
17
select datediff(ms,@timediff,getdate()) as 耗时
18
set nocount off;
19
end
20
create procedure proc_paged_with_Rownumber --利用SQL 2005中的Row_number()
2
(
3
@pageIndex int,
4
@pageSize int
5
)
6
as
7
declare @timediff datetime
8
begin
9
set nocount on;
10
select @timediff=getdate()
11
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)
12
select datediff(ms,@timediff,getdate()) as 耗时
13
set nocount off;
14
end
15
create procedure proc_CTE --利用临时表及Row_number
2
(
3
@pageIndex int, --页索引
4
@pageSize int --页记录数
5
)
6
as
7
set nocount on;
8
declare @ctestr nvarchar(400)
9
declare @strSql nvarchar(400)
10
declare @datediff datetime
11
begin
12
select @datediff=GetDate()
13
set @ctestr='with Table_CTE as
14
(select ceiling((Row_number() over(order by ID ASC))/'+str(@pageSize)+') as page_num,* from tb_TestTable)';
15
set @strSql=@ctestr+' select * From Table_CTE where page_num='+str(@pageIndex)
16
end
17
begin
18
execute sp_executesql @strSql
19
select datediff(ms,@datediff,GetDate())
20
set nocount off;
21
end
22
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 -------*/ 2
--/*-----存储过程 分页处理 浪尘 2008-9-1修改----------*/ 3
--/*----- 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 -------*/ 4

5
alter PROCEDURE proc_paged_2part_selectMax 6
( 7
@tblName nvarchar(200), ----要显示的表或多个表的连接 8
@fldName nvarchar(500) = '*', ----要显示的字段列表 9
@pageSize int = 10, ----每页显示的记录个数 10
@page int = 1, ----要显示那一页的记录 11
@fldSort nvarchar(200) = null, ----排序字段列表或条件 12
@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 ') 13
@strCondition nvarchar(1000) = null, ----查询条件,不需where 14
@ID nvarchar(150), ----主表的主键 15
@Dist bit = 0, ----是否添加查询字段的 DISTINCT 默认0不添加/1添加 16
@pageCount int = 1 output, ----查询结果分页后的总页数 17
@Counts int = 1 output ----查询到的记录数 18
) 19
AS 20
SET NOCOUNT ON 21
Declare @sqlTmp nvarchar(1000) ----存放动态生成的SQL语句 22
Declare @strTmp nvarchar(1000) ----存放取得查询结果总数的查询语句 23
Declare @strID nvarchar(1000) ----存放取得查询开头或结尾ID的查询语句 24

25
Declare @strSortType nvarchar(10) ----数据排序规则A 26
Declare @strFSortType nvarchar(10) ----数据排序规则B 27

28
Declare @SqlSelect nvarchar(50) ----对含有DISTINCT的查询进行SQL构造 29
Declare @SqlCounts nvarchar(50) ----对含有DISTINCT的总数查询进行SQL构造 30

31
declare @timediff datetime --耗时测试时间差 32
select @timediff=getdate() 33

34
if @Dist = 0 35
begin 36
set @SqlSelect = 'select ' 37
set @SqlCounts = 'Count(*)' 38
end 39
else 40
begin 41
set @SqlSelect = 'select distinct ' 42
set @SqlCounts = 'Count(DISTINCT '+@ID+')' 43
end 44

45

46
if @Sort=0 47
begin 48
set @strFSortType=' ASC ' 49
set @strSortType=' DESC ' 50
end 51
else 52
begin 53
set @strFSortType=' DESC ' 54
set @strSortType=' ASC ' 55
end 56

57

58

59
--------生成查询语句-------- 60
--此处@strTmp为取得查询结果数量的语句 61
if @strCondition is null or @strCondition='' --没有设置显示条件 62
begin 63
set @sqlTmp = @fldName + ' From ' + @tblName 64
set @strTmp = @SqlSelect+' @Counts='+@SqlCounts+' FROM '+@tblName 65
set @strID = ' From ' + @tblName 66
end 67
else 68
begin 69
set @sqlTmp = + @fldName + 'From ' + @tblName + ' where (1>0) ' + @strCondition 70
set @strTmp = @SqlSelect+' @Counts='+@SqlCounts+' FROM '+@tblName + ' where (1>0) ' + @strCondition 71
set @strID = ' From ' + @tblName + ' where (1>0) ' + @strCondition 72
end 73

74
----取得查询结果总数量----- 75
exec sp_executesql @strTmp,N'@Counts int out ',@Counts out 76
declare @tmpCounts int 77
if @Counts = 0 78
set @tmpCounts = 1 79
else 80
set @tmpCounts = @Counts 81

82
--取得分页总数 83
set @pageCount=(@tmpCounts+@pageSize-1)/@pageSize 84

85
/**//**当前页大于总页数 取最后一页**/ 86
if @page>@pageCount 87
set @page=@pageCount 88

89
--/*-----数据分页2分处理-------*/ 90
declare @pageIndex int --总数/页大小 91
declare @lastcount int --总数%页大小 92

93
set @pageIndex = @tmpCounts/@pageSize 94
set @lastcount = @tmpCounts%@pageSize 95
if @lastcount > 0 96
set @pageIndex = @pageIndex + 1 97
else 98
set @lastcount = @pagesize 99

100
--//***显示分页 101
if @strCondition is null or @strCondition='' --没有设置显示条件 102
begin 103
if @pageIndex<2 or @page<=@pageIndex / 2 + @pageIndex % 2 --前半部分数据处理 104
begin 105
if @page=1 106
set @strTmp=@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName 107
+' order by '+ @fldSort +' '+ @strFSortType 108
else 109
begin 110
if @Sort=1 111
begin 112
set @strTmp=@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName 113
+' where '+@ID+' <(select min('+ @ID +') from ('+ @SqlSelect+' top '+ CAST(@pageSize*(@page-1) as Varchar(20)) +' '+ @ID +' from '+@tblName 114
+' order by '+ @fldSort +' '+ @strFSortType+') AS TBMinID)' 115
+' order by '+ @fldSort +' '+ @strFSortType 116
end 117
else 118
begin 119
set @strTmp=@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName 120
+' where '+@ID+' >(select max('+ @ID +') from ('+ @SqlSelect+' top '+ CAST(@pageSize*(@page-1) as Varchar(20)) +' '+ @ID +' from '+@tblName 121
+' order by '+ @fldSort +' '+ @strFSortType+') AS TBMinID)' 122
+' order by '+ @fldSort +' '+ @strFSortType 123
end 124
end 125
end 126
else 127
begin 128
set @page = @pageIndex-@page+1 --后半部分数据处理 129
if @page <= 1 --最后一页数据显示 130
set @strTmp=@SqlSelect+' * from ('+@SqlSelect+' top '+ CAST(@lastcount as VARCHAR(4))+' '+ @fldName+' from '+@tblName 131
+' order by '+ @fldSort +' '+ @strSortType+') AS TempTB'+' order by '+ @fldSort +' '+ @strFSortType 132
else 133
if @Sort=1 134
begin 135
set @strTmp=@SqlSelect+' * from ('+@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName 136
+' where '+@ID+' >(select max('+ @ID +') from('+ @SqlSelect+' top '+ CAST(@pageSize*(@page-2)+@lastcount as Varchar(20)) +' '+ @ID +' from '+@tblName 137
+' order by '+ @fldSort +' '+ @strSortType+') AS TBMaxID)' 138
+' order by '+ @fldSort +' '+ @strSortType+') AS TempTB'+' order by '+ @fldSort +' '+ @strFSortType 139
end 140
else 141
begin 142
set @strTmp=@SqlSelect+' * from ('+@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName 143
+' where '+@ID+' <(select min('+ @ID +') from('+ @SqlSelect+' top '+ CAST(@pageSize*(@page-2)+@lastcount as Varchar(20)) +' '+ @ID +' from '+@tblName 144
+' order by '+ @fldSort +' '+ @strSortType+') AS TBMaxID)' 145
+' order by '+ @fldSort +' '+ @strSortType+') AS TempTB'+' order by '+ @fldSort +' '+ @strFSortType 146
end 147
end 148
end 149

150
else --有查询条件 151
begin 152
if @pageIndex<2 or @page<=@pageIndex / 2 + @pageIndex % 2 --前半部分数据处理 153
begin 154
if @page=1 155
set @strTmp=@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName 156
+' where 1=1 ' + @strCondition + ' order by '+ @fldSort +' '+ @strFSortType 157
else if(@Sort=1) 158
begin 159
set @strTmp=@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName 160
+' where '+@ID+' <(select min('+ @ID +') from ('+ @SqlSelect+' top '+ CAST(@pageSize*(@page-1) as Varchar(20)) +' '+ @ID +' from '+@tblName 161
+' where (1=1) ' + @strCondition +' order by '+ @fldSort +' '+ @strFSortType+') AS TBMinID)' 162
+' '+ @strCondition +' order by '+ @fldSort +' '+ @strFSortType 163
end 164
else 165
begin 166
set @strTmp=@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName 167
+' where '+@ID+' >(select max('+ @ID +') from ('+ @SqlSelect+' top '+ CAST(@pageSize*(@page-1) as Varchar(20)) +' '+ @ID +' from '+@tblName 168
+' where (1=1) ' + @strCondition +' order by '+ @fldSort +' '+ @strFSortType+') AS TBMinID)' 169
+' '+ @strCondition +' order by '+ @fldSort +' '+ @strFSortType 170
end 171
end 172
else 173
begin 174
set @page = @pageIndex-@page+1 --后半部分数据处理 175
if @page <= 1 --最后一页数据显示 176
set @strTmp=@SqlSelect+' * from ('+@SqlSelect+' top '+ CAST(@lastcount as VARCHAR(4))+' '+ @fldName+' from '+@tblName 177
+' where (1=1) '+ @strCondition +' order by '+ @fldSort +' '+ @strSortType+') AS TempTB'+' order by '+ @fldSort +' '+ @strFSortType 178
else if(@Sort=1) 179
set @strTmp=@SqlSelect+' * from ('+@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName 180
+' where '+@ID+' >(select max('+ @ID +') from('+ @SqlSelect+' top '+ CAST(@pageSize*(@page-2)+@lastcount as Varchar(20)) +' '+ @ID +' from '+@tblName 181
+' where (1=1) '+ @strCondition +' order by '+ @fldSort +' '+ @strSortType+') AS TBMaxID)' 182
+' '+ @strCondition+' order by '+ @fldSort +' '+ @strSortType+') AS TempTB'+' order by '+ @fldSort +' '+ @strFSortType 183
else 184
set @strTmp=@SqlSelect+' * from ('+@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from '+@tblName 185
+' where '+@ID+' <(select min('+ @ID +') from('+ @SqlSelect+' top '+ CAST(@pageSize*(@page-2)+@lastcount as Varchar(20)) +' '+ @ID +' from '+@tblName 186
+' where (1=1) '+ @strCondition +' order by '+ @fldSort +' '+ @strSortType+') AS TBMaxID)' 187
+' '+ @strCondition+' order by '+ @fldSort +' '+ @strSortType+') AS TempTB'+' order by '+ @fldSort +' '+ @strFSortType 188
end 189
end 190

191
------返回查询结果----- 192
exec sp_executesql @strTmp 193
select datediff(ms,@timediff,getdate()) as 耗时 194
--print @strTmp 195
SET NOCOUNT OFF 196
GO197

执行示例:exec proc_paged_2part_selectMax 'tb_testTable','ID,userName,userPWD,userEmail',10,100000,'ID',0,null,'ID',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。
本文通过实验对比了五种常见分页算法在不同页数下的效率,包括利用select top和select not in、select max等方法,并引入2分法优化select max算法,显著提升了大数据量下的分页性能。
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