使用Oracle Partition Table对日志表进行分区
某个系统中有个日志型的表，现在的大小大概超过500MB，与该表相关的语句的执行计划都是对这个表进行全表扫描。 下面是该表
某个系统中有个日志型的表，现在的大小大概超过500MB，与该表相关的语句的执行计划都是对这个表进行全表扫描。
下面是该表的定义：
01 create table p_siteaccesslog
02 (
03 logID varchar(40) not null,
04 infoType varchar(20) default 'site',
05 siteId varchar(30),
06 columnId varchar(30),
07 infoId varchar(30),
08 url varchar(300),
09 location varchar(80),
10 action varchar(20),
11 accessDate varchar(10),
12 accessTime varchar(8),
13 sessionID varchar(90),
14 userName varchar(30),
15 userBrowser varchar(50),
16 userOS varchar(30),
17 userIp varchar(30),
18 localization varchar(100),
19 constraint PK_p_siteaccesslog primary key (logID)
20 )
该表有一个主键，为每条日志分配一个主键，感觉上一百年都不会用上这个主键来查一次数据。所以在新的分区表上将其去掉。
1 test$ora8i@4.20 SQL> l
2 1* select segment_name,sum(bytes/1048576) MB from user_extents group by segment_name order by 2 desc
3 test$ora8i@4.20 SQL> /
4
5 SEGMENT_NAME MB
6 ---------------------------------------- ----------
7 P_SITEACCESSLOG 536
由于是日志型的表，第一感觉就是按照时间分区，并淘汰（切换）旧的数据。
于是沿着这个思路，，按照每月一个分区的策略构建分区表：
01 create table my_p_siteaccesslog
02 (
03 logID varchar(40) not null,
04 infoType varchar(20) default 'site',
05 siteId varchar(30),
06 columnId varchar(30),
07 infoId varchar(30),
08 url varchar(300),
09 location varchar(80),
10 action varchar(20),
11 accessDate varchar(10),
12 accessTime varchar(8),
13 sessionID varchar(90),
14 userName varchar(30),
15 userBrowser varchar(50),
16 userOS varchar(30),
17 userIp varchar(30),
18 localization varchar(100)
19 )
20 partition by range (accessDate)
21 (
22 partition pbf2009 values less than ('2009-01-01'),
23 partition p200901 values less than ('2009-02-01'),
24 partition p200902 values less than ('2009-03-01'),
25 partition p200903 values less than ('2009-04-01'),
26 partition p200904 values less than ('2009-05-01'),
27 partition p200905 values less than ('2009-06-01'),
28 partition p200906 values less than ('2009-07-01'),
29 partition p200907 values less than ('2009-08-01'),
30 partition p200908 values less than ('2009-09-01'),
31 partition p200909 values less than ('2009-10-01'),
32 partition p200910 values less than ('2009-11-01'),
33 partition p200911 values less than ('2009-12-01'),
34 partition p200912 values less than ('2010-01-01'),
35 partition p201001 values less than ('2010-02-01'),
36 partition p201002 values less than ('2010-03-01'),
37 partition p201003 values less than ('2010-04-01'),
38 partition p201004 values less than ('2010-05-01'),
39 partition p201005 values less than ('2010-06-01'),
40 partition p201006 values less than ('2010-07-01'),
41 partition p201007 values less than ('2010-08-01'),
42 partition p201008 values less than ('2010-09-01'),
43 partition p201009 values less than ('2010-10-01'),
44 partition p201010 values less than ('2010-11-01'),
45 partition p201011 values less than ('2010-12-01'),
46 partition p201012 values less than ('2011-01-01')
47 )