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
3use data_Test
4GO
5create 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)
12GO
然后我们在数据表中插入2000000条数据:
1--插入数据
2set identity_insert tb_TestTable on
3declare @count int
4set @count=1
5while @count<=2000000
6begin
7 insert into tb_TestTable(id,userName,userPWD,userEmail) values(@count,'admin','admin888','')
8 set @count=@count+1
9end
10set 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：
1create 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)
6as
7begin
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;
16end
2,利用select top 和 select max(列键)
1create 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)
6as
7begin
8set 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
15set nocount off;
16end
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
1create 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)
6as
7 declare @count int
8 declare @ID int
9 declare @timediff datetime
10 declare @sql nvarchar(500)
11begin
12set nocount on;
13 select @count=0,@ID=0,@timediff=getdate()
14 select @count=@count+1,@ID=case when @count<[url=mailto:=@pageSize*@pageIndex]=@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
18set nocount off;
19end
20
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
1create procedure proc_paged_with_Rownumber --利用SQL 2005中的Row_number()
2(
3 @pageIndex int,
4 @pageSize int
5)
6as
7 declare @timediff datetime
8begin
9set 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
13set nocount off;
14end
15
5，利用临时表及Row_number
1create 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)
6as
7 set nocount on;
8 declare @ctestr nvarchar(400)
9 declare @strSql nvarchar(400)
10 declare @datediff datetime
11begin
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)
16end
17 begin
18 execute sp_executesql @strSql
19 select datediff(ms,@datediff,GetDate())
20 set nocount off;
21 end
22
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
| 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。
1--/*-----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
5alter PROCEDURE proc_paged_2part_selectMax
6(
[url=mailto:7@tblName]7@tblName nvarchar(200), ----要显示的表或多个表的连接
[url=mailto:8@fldName]8@fldName nvarchar(500) = '*', ----要显示的字段列表
[url=mailto:9@pageSize]9@pageSize int = 10, ----每页显示的记录个数
[url=mailto:10@page]10@page int = 1, ----要显示那一页的记录
[url=mailto:11@fldSort]11@fldSort nvarchar(200) = null, ----排序字段列表或条件
[url=mailto:12@Sort]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 ')
[url=mailto:13@strCondition]13@strCondition nvarchar(1000) = null, ----查询条件,不需where
[url=mailto:14@ID]14@ID nvarchar(150), ----主表的主键
[url=mailto:15@Dist]15@Dist bit = 0, ----是否添加查询字段的 DISTINCT 默认0不添加/1添加
[url=mailto:16@pageCount]16@pageCount int = 1 output, ----查询结果分页后的总页数
[url=mailto:17@Counts]17@Counts int = 1 output ----查询到的记录数
18)
19AS
20SET NOCOUNT ON
21Declare @sqlTmp nvarchar(1000) ----存放动态生成的SQL语句
22Declare @strTmp nvarchar(1000) ----存放取得查询结果总数的查询语句
23Declare @strID nvarchar(1000) ----存放取得查询开头或结尾ID的查询语句
24
25Declare @strSortType nvarchar(10) ----数据排序规则A
26Declare @strFSortType nvarchar(10) ----数据排序规则B
27
28Declare @SqlSelect nvarchar(50) ----对含有DISTINCT的查询进行SQL构造
29Declare @SqlCounts nvarchar(50) ----对含有DISTINCT的总数查询进行SQL构造
30
31declare @timediff datetime --耗时测试时间差
32select @timediff=getdate()
33
34if @Dist = 0
35begin
36 set @SqlSelect = 'select '
37 set @SqlCounts = 'Count(*)'
38end
39else
40begin
41 set @SqlSelect = 'select distinct '
42 set @SqlCounts = 'Count(DISTINCT [url=mailto:]'+@ID+')'
43end
44
45
46if @Sort=0
47begin
48 set @strFSortType=' ASC '
49 set @strSortType=' DESC '
50end
51else
52begin
53 set @strFSortType=' DESC '
54 set @strSortType=' ASC '
55end
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
61if @strCondition is null or @strCondition='' --没有设置显示条件
62begin
63 set @sqlTmp = @fldName + ' From ' + @tblName
64 set @strTmp = @SqlSelect+' @Counts='+@SqlCounts+' FROM [url=mailto:]'+@tblName
65 set @strID = ' From ' + @tblName
66end
67else
68begin
69 set @sqlTmp = + @fldName + 'From ' + @tblName + ' where (1>0) ' + @strCondition
70 set @strTmp = @SqlSelect+' @Counts='+@SqlCounts+' FROM [url=mailto:]'+@tblName + ' where (1>0) ' + @strCondition
71 set @strID = ' From ' + @tblName + ' where (1>0) ' + @strCondition
72end
73
74----取得查询结果总数量-----
75exec sp_executesql @strTmp,N'@Counts int out ',@Counts out
76declare @tmpCounts int
77if @Counts = 0
78 set @tmpCounts = 1
79else
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<[url=mailto:=@pageIndex]=@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 [url=mailto:]'+@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 [url=mailto:]'+@tblName
113 +' where [url=mailto:]'+@ID+' <(select min('+ @ID +') from ('+ @SqlSelect+' top '+ CAST(@pageSize*(@page-1) as Varchar(20)) +' '+ @ID +' from [url=mailto:]'+@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 [url=mailto:]'+@tblName
120 +' where [url=mailto:]'+@ID+' >(select max('+ @ID +') from ('+ @SqlSelect+' top '+ CAST(@pageSize*(@page-1) as Varchar(20)) +' '+ @ID +' from [url=mailto:]'+@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 ([url=mailto:]'+@SqlSelect+' top '+ CAST(@lastcount as VARCHAR(4))+' '+ @fldName+' from [url=mailto:]'+@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 ([url=mailto:]'+@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from [url=mailto:]'+@tblName
136 +' where [url=mailto:]'+@ID+' >(select max('+ @ID +') from('+ @SqlSelect+' top '+ CAST(@pageSize*(@page-2)+@lastcount as Varchar(20)) +' '+ @ID +' from [url=mailto:]'+@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 ([url=mailto:]'+@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from [url=mailto:]'+@tblName
143 +' where [url=mailto:]'+@ID+' <(select min('+ @ID +') from('+ @SqlSelect+' top '+ CAST(@pageSize*(@page-2)+@lastcount as Varchar(20)) +' '+ @ID +' from [url=mailto:]'+@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<[url=mailto:=@pageIndex]=@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 [url=mailto:]'+@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 [url=mailto:]'+@tblName
160 +' where [url=mailto:]'+@ID+' <(select min('+ @ID +') from ('+ @SqlSelect+' top '+ CAST(@pageSize*(@page-1) as Varchar(20)) +' '+ @ID +' from [url=mailto:]'+@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 [url=mailto:]'+@tblName
167 +' where [url=mailto:]'+@ID+' >(select max('+ @ID +') from ('+ @SqlSelect+' top '+ CAST(@pageSize*(@page-1) as Varchar(20)) +' '+ @ID +' from [url=mailto:]'+@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 ([url=mailto:]'+@SqlSelect+' top '+ CAST(@lastcount as VARCHAR(4))+' '+ @fldName+' from [url=mailto:]'+@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 ([url=mailto:]'+@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from [url=mailto:]'+@tblName
180 +' where [url=mailto:]'+@ID+' >(select max('+ @ID +') from('+ @SqlSelect+' top '+ CAST(@pageSize*(@page-2)+@lastcount as Varchar(20)) +' '+ @ID +' from [url=mailto:]'+@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 ([url=mailto:]'+@SqlSelect+' top '+ CAST(@pageSize as VARCHAR(4))+' '+ @fldName+' from [url=mailto:]'+@tblName
185 +' where [url=mailto:]'+@ID+' <(select min('+ @ID +') from('+ @SqlSelect+' top '+ CAST(@pageSize*(@page-2)+@lastcount as Varchar(20)) +' '+ @ID +' from [url=mailto:]'+@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-----
192exec sp_executesql @strTmp
193select datediff(ms,@timediff,getdate()) as 耗时
194--print @strTmp
195SET NOCOUNT OFF
196GO
197
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。
