#
Partitioned Tables
--
Range Partitioning Example
CREATE
TABLE
sales_range
(salesman_id
NUMBER
(
5
),
salesman_name
VARCHAR2
(
30
),
sales_amount
NUMBER
(
10
),
sales_date DATE)
PARTITION
BY
RANGE(sales_date)
(
PARTITION sales_jan2006
VALUES
LESS THAN(TO_DATE(
'
02/01/2006
'
,
'
MM/DD/YYYY
'
)),
PARTITION sales_feb2006
VALUES
LESS THAN(TO_DATE(
'
03/01/2006
'
,
'
MM/DD/YYYY
'
)),
PARTITION sales_mar2006
VALUES
LESS THAN(TO_DATE(
'
04/01/2006
'
,
'
MM/DD/YYYY
'
)),
PARTITION sales_apr2006
VALUES
LESS THAN(TO_DATE(
'
05/01/2006
'
,
'
MM/DD/YYYY
'
)),
PARTITION sales_may2006
VALUES
LESS THAN(TO_DATE(
'
06/01/2006
'
,
'
MM/DD/YYYY
'
))
);
insert
into
sales_range
values
(
12345
,
'
test
'
,
1000
, to_date(
'
2006-01-15
'
,
'
yyyy-mm-dd
'
));
insert
into
sales_range
values
(
12345
,
'
test
'
,
1000
, to_date(
'
2006-02-15
'
,
'
yyyy-mm-dd
'
));
insert
into
sales_range
values
(
12345
,
'
test
'
,
1000
, to_date(
'
2006-03-15
'
,
'
yyyy-mm-dd
'
));
insert
into
sales_range
values
(
12345
,
'
test
'
,
1000
, to_date(
'
2006-04-15
'
,
'
yyyy-mm-dd
'
));
insert
into
sales_range
values
(
12345
,
'
test
'
,
1000
, to_date(
'
2006-05-15
'
,
'
yyyy-mm-dd
'
));
create
index
idx_sales_range_sales_date
on
sales_range (sales_date);
ALTER
TABLE
sales_range
DROP
PARTITION sales_jan2006
UPDATE
GLOBAL INDEXES;
When to Partition a Table
Here are some suggestions for when to partition a table:
- Tables greater than 2GB should always be considered for partitioning.
- Tables containing historical data, in which new data is added into the newest partition. A typical example is a historical table where only the current month's data is updatable and the other 11 months are read-only.
参考: ora92_doc/server.920/a96524/c12parti.htm
详细请参考oracle文档
yahoo的邮箱容量已经增加至3.5G, 好大啊. 不过还是喜欢gmail.
The goal of Tobago is to provide the community with a well designed set of user interface components based on JSF and run on MyFaces.
Introduction
Demo
http://extremecomponents.org/wiki/index.php/Simplified_Chinese_Tutorials_Limit
上面的版本是mysql
oracle的分页实现, 在传参数时增加limit.getRowStart()即可
public String limitQuery(int rowStart, int rowEnd, String query) {
String querySql = "select * from ( " +
" select my_table.*, rownum my_rownum from ( " +
query +
" ) my_table where rownum <= " + rowEnd +
") where my_rownum > " + rowStart;
return querySql;
}
Intel Mac能够运行OS X和XP，还是有诱惑力的，但两万块左右MacBook Pro对于普通老百姓来说太贵了．
FlyakiteOSX, 让我的xp变成mac os x, 爽
用idea创建war文件时(J2EE Build Settings|Create web module war file)，老是将所有jar复制到WEB-INF/lib下，一直羡慕JBuilder的exclude, include功能。
原来idea也有这个功能，在Web Module Settings | Modules and Libraries to Package下，选择Do not package即可。
IDEA Struts Plugin: Struts Assistant
1. 安装: 在idea plugins下载并安装
2. 配置: 指定struts解压包的路径
1. Using lazy property fetching
To enable lazy property loading, set the lazy attribute on your particular property mappings:
<class name="Document">
<id name="id">
<generator class="native"/>
</id>
<property name="name" not-null="true" length="50"/>
<property name="summary" not-null="true" length="200" lazy="true"/>
<property name="text" not-null="true" length="2000" lazy="true"/>
</class>
Lazy property loading requires buildtime bytecode instrumentation! If your persistent classes are not enhanced, Hibernate will silently ignore lazy property settings and fall back to immediate fetching.
For bytecode instrumentation, use the following Ant task:
<target name="instrument" depends="compile">
<taskdef name="instrument" classname="org.hibernate.tool.instrument.InstrumentTask">
<classpath path="${jar.path}"/>
<classpath path="${classes.dir}"/>
<classpath refid="lib.class.path"/>
</taskdef>
<instrument verbose="true">
<fileset dir="${testclasses.dir}/org/hibernate/auction/model">
<include name="*.class"/>
</fileset>
</instrument>
</target>Please note that this is mostly a marketing feature, as in practice, optimizing row reads is much more important than optimization of column reads.
debug麻烦, 并没有测试
2. use hql
// use vo
String hql = "select new Foo(f.id, f.name) from Foo f";
// use map
String hql = "select new map(f.id, f.name) from Foo f";
// use Object[]
String hql = "select f.id, f.name from Foo f";
// use list
String "select new list(f.id, f.name) from Foo f"; 不支持嵌套的对象, 不爽, 如
String hql = "select new Foo(f.id, new Bar(f.bar.id, f.bar.name)) from Foo f"; 以上两种方法在实际应用中都不是很理想, 但那种from Pojo的方式太浪费内存, 遇到
blob字段更可怕, 有其他更好方法的请告知
前几个星期刚换电脑的主机, 但这几天人脑又出问题(偏头痛).
电脑坏了可以再买, 人脑坏了, 麻烦.