基于 ROWID 的物化视图

SQL> create table skytest(a number primary key);

Table created.

SQL> create materialized view log on skytest with rowid;

Materialized view log created.

SQL> select object_name,object_type from user_objects
  2  where object_name like '%SKYTEST%';

OBJECT_NAME                    OBJECT_TYPE
------------------------------ ------------------
MLOG$_SKYTEST                  TABLE
SKYTEST                        TABLE

SQL> create materialized view MV_SKYTEST
  2  REFRESH FAST
  3  as
  4  select * from skytest;
select * from skytest
              *
ERROR at line 4:
ORA-23415: snapshot log for "ORACLE"."SKYTEST" does not record the primary key

Oracle 8 开始默认使用 Primary Key 方式。

Materialized view created.

SQL> select object_name,object_type from user_objects
  2  where object_name like '%SKYTEST%';

OBJECT_NAME                    OBJECT_TYPE
------------------------------ ------------------
I_SNAP$_MV_SKYTEST             INDEX
MLOG$_SKYTEST                  TABLE
MV_SKYTEST                     TABLE
MV_SKYTEST                     UNDEFINED
SKYTEST                        TABLE

        可以看到除了多了物化视图 MV_SKYTEST 之外，还多了一个索引 I_SNAP$_MV_SKYTEST 和一个表 MLOG$_SKYTEST

SQL> desc MLOG$_SKYTEST
 Name                                        Null?    Type
 ------------------------------------------- -------- -------------------
 M_ROW$$                                              VARCHAR2(255)
 SNAPTIME$$                                           DATE
 DMLTYPE$$                                            VARCHAR2(1)
 OLD_NEW$$                                            VARCHAR2(1)
 CHANGE_VECTOR$$                                      RAW(255)

       MLOG$_SKYTEST 表中记录了主表上修改的记录，M_ROW$$ 保存主表上修改行的 ROWID，这样可以定位修改的行。

SQL> select INDEX_NAME,INDEX_TYPE,TABLE_NAME,UNIQUENESS,STATUS,GENERATED from dba_indexes
  2  where index_name='I_SNAP$_MV_SKYTEST';

INDEX_NAME                     INDEX_TYPE                  TABLE_NAME                     UNIQUENES STATUS   G
------------------------------ --------------------------- ------------------------------ --------- -------- -
I_SNAP$_MV_SKYTEST             NORMAL                      MV_SKYTEST                     UNIQUE    VALID    N

SQL> select table_name,index_name,column_name from dba_ind_columns
  2  where index_name='I_SNAP$_MV_SKYTEST';

TABLE_NAME                     INDEX_NAME                     COLUMN_NAME
------------------------------ ------------------------------ ------------------------------
MV_SKYTEST                     I_SNAP$_MV_SKYTEST             M_ROW$$

SQL> select table_name,column_name from dba_tab_columns
  2  where table_name='MV_SKYTEST';

TABLE_NAME                     COLUMN_NAME
------------------------------ ------------------------------
MV_SKYTEST                     A

       I_SNAP$_MV_SKYTEST 是建立在物化视图 MV_SKYTEST 中 M_ROW$$ 隐藏列上的唯一索引，该列正是保存了主表上对应行的 ROWID 值，建立该索引应该是为了提高刷新的性能。

       另外一个类型为 UNDEFINED，名字和物化视图一样的东东不知道是干吗的。

基于 Primary Key 的物化视图

SQL> drop materialized view MV_SKYTEST;

Materialized view dropped.

SQL> drop materialized view log on SKYTEST;

Materialized view log dropped.

SQL> select object_name,object_type from user_objects
  2  where object_name like '%SKYTEST%';

OBJECT_NAME                    OBJECT_TYPE
------------------------------ ------------------
SKYTEST                        TABLE

SQL> create materialized view log on SKYTEST;

Materialized view log created.

SQL> select object_name,object_type from user_objects
  2  where object_name like '%SKYTEST%';

OBJECT_NAME                    OBJECT_TYPE
------------------------------ ------------------
MLOG$_SKYTEST                  TABLE
RUPD$_SKYTEST                  TABLE
SKYTEST                        TABLE

SQL> create materialized view MV_SKYTEST
  2  REFRESH FAST
  3  as
  4  select * from skytest;

Materialized view created.

SQL> select object_name,object_type from user_objects
  2  where object_name like '%SKYTEST%';

OBJECT_NAME                    OBJECT_TYPE
------------------------------ ------------------
MLOG$_SKYTEST                  TABLE
MV_SKYTEST                     TABLE
MV_SKYTEST                     UNDEFINED
RUPD$_SKYTEST                  TABLE
SKYTEST                        TABLE

SQL> desc MLOG$_SKYTEST
 Name                                                                                Null?    Type
 ----------------------------------------------------------------------------------- -------- --------------------------------------------------------
 A                                                                                            NUMBER
 SNAPTIME$$                                                                                   DATE
 DMLTYPE$$                                                                                    VARCHAR2(1)
 OLD_NEW$$                                                                                    VARCHAR2(1)
 CHANGE_VECTOR$$                                                                              RAW(255)

SQL> desc RUPD$_SKYTEST
 Name                                                                                Null?    Type
 ----------------------------------------------------------------------------------- -------- --------------------------------------------------------
 A                                                                                            NUMBER
 DMLTYPE$$                                                                                    VARCHAR2(1)
 SNAPID                                                                                       NUMBER(38)
 CHANGE_VECTOR$$                                                                              RAW(255)

       此时 mlog 中保存了 Primary Key。RUPD$_ 开头的表用于可更新的基于 Primary Key 的物化视图。

SQL> select INDEX_NAME,INDEX_TYPE,TABLE_NAME,UNIQUENESS,STATUS,GENERATED from dba_indexes
  2  where table_name in ('SKYTEST','MV_SKYTEST'); 

INDEX_NAME                     INDEX_TYPE                  TABLE_NAME                     UNIQUENES STATUS   G
------------------------------ --------------------------- ------------------------------ --------- -------- -
SYS_C001221                    NORMAL                      SKYTEST                        UNIQUE    VALID    Y
SYS_C001224                    NORMAL                      MV_SKYTEST                     UNIQUE    VALID    Y

SQL> select CONSTRAINT_NAME,CONSTRAINT_TYPE,DEFERRABLE,DEFERRED,GENERATED from dba_constraints
  2  where table_name in ('SKYTEST','MV_SKYTEST');

CONSTRAINT_NAME                C DEFERRABLE     DEFERRED  GENERATED
------------------------------ - -------------- --------- --------------
SYS_C001221                    P NOT DEFERRABLE IMMEDIATE GENERATED NAME
SYS_C001224                    P NOT DEFERRABLE IMMEDIATE GENERATED NAME

       同时，Oracle 也会在物化视图上建立相应的 Primary Key。不过对此我比较疑惑，由于刷新机制的缘故，Oracle 是不建议在物化视图上使用 Primary/Unique constraint 的，而建议使用 non unique index + deferred constraint 的形式，参见：Note:284101.1

       最后要说明的是，在创建物化视图日志时可以同时指定 WITH ROWID 和 WITH PRIMARY KEY。此时，在物化视图日志中两者都会保存，但最终物化视图是哪种类型的则是在创建物化视图时决定（只能指定 WITH ROWID 和 WITH PRIMARY KEY 其中一个）。如果所有的物化视图都是同一种类型的，那么建议在创建物化视图时也只指定那一种类型，可以减少空间消耗提高刷新性能。

参考：

Oracle materialized view mlog$ table

Differences Between Rowid & Primary Key Materialized Views
Note:254593.1

Fast Refresh Causing ORA-1/ORA-2291/ORA-2292, Complete Refresh Works Fine
Note:284101.1

希望导出测试表中日期为 2007-09-22 的一条数据：

SQL> select * from skytest;

       SID DT
---------- -----------------
         1 20070913 00:00:00
         2 20070914 00:00:00
         3 20070915 00:00:00
         4 20070916 00:00:00
         5 20070917 00:00:00
         6 20070918 00:00:00
         7 20070919 00:00:00
         8 20070920 00:00:00
         9 20070921 00:00:00
        10 20070922 00:00:00
        12 20070924 00:00:00

11 rows selected.

凭印象按照以下格式运行：

exp / tables=skytest file=test.dmp query=\"where dt=to_date(\'2007-09-22\',\'yyyy-mm-dd\')\"

ksh: syntax error: `(' unexpected

其实文档中讲得很清楚：

exp scott/tiger TABLES=emp QUERY=\"WHERE job=\'SALESMAN\' and sal \<1600\"

Note:
Because the value of the QUERY parameter contains blanks, most operating systems require that the entire strings WHERE job=\'SALESMAN\' and sal\<1600 be placed in double quotation marks or marked as a literal by some method. Operating system reserved characters also need to be preceded by an escape character. See your Oracle operating system-specific documentation for information about special and reserved characters on your system.

所有操作系统保留字符都要使用转义符号，看来 ( ) 也需要转义。

正确的写法：

oracle DBALNP01 > exp / tables=skytest file=test.dmp query=\"where dt=to_date\(\'2007-09-22\',\'yyyy-mm-dd\'\)\"

Export: Release 8.1.7.4.0 - Production on Wed Sep 12 04:30:45 2007

(c) Copyright 2000 Oracle Corporation.  All rights reserved.

Connected to: Oracle8i Enterprise Edition Release 8.1.7.4.0 - Production
With the Partitioning option
JServer Release 8.1.7.4.0 - Production
Export done in US7ASCII character set and US7ASCII NCHAR character set

About to export specified tables via Conventional Path ...
. . exporting table                        SKYTEST          1 rows exported
Export terminated successfully without warnings.

简洁的写法：
如果环境变量设置合适，就不需要使用 to_date 函数了

oracle DBALNP01 > exp / tables=skytest file=test.dmp query=\"where dt=\'20070922\'\"

Export: Release 8.1.7.4.0 - Production on Wed Sep 12 04:25:56 2007

(c) Copyright 2000 Oracle Corporation.  All rights reserved.

Connected to: Oracle8i Enterprise Edition Release 8.1.7.4.0 - Production
With the Partitioning option
JServer Release 8.1.7.4.0 - Production
Export done in US7ASCII character set and US7ASCII NCHAR character set

About to export specified tables via Conventional Path ...
. . exporting table                        SKYTEST          1 rows exported
Export terminated successfully without warnings.

任何 os 平台都适用的方法（推荐）：
以上两种方法并不一定适合其他操作系统，不过使用 parfile 就不用担心这些格式问题

oracle DBALNP01 > cat > test.par
tables=skytest
file=test.dmp
query="where dt=to_date('2007-09-22','yyyy-mm-dd')"

oracle DBALNP01 > exp / parfile=test.par

Export: Release 8.1.7.4.0 - Production on Wed Sep 12 04:22:27 2007

(c) Copyright 2000 Oracle Corporation.  All rights reserved.

Connected to: Oracle8i Enterprise Edition Release 8.1.7.4.0 - Production
With the Partitioning option
JServer Release 8.1.7.4.0 - Production
Export done in US7ASCII character set and US7ASCII NCHAR character set

About to export specified tables via Conventional Path ...
. . exporting table                        SKYTEST          1 rows exported
Export terminated successfully without warnings.

不需要任何转义符既简洁又可以在多种操作系统平台上通用，推荐使用这种方式。

参考：http://www.itpub.net/683793.html

:s/vivian/sky/ 替换当前行第一个 vivian 为 sky
:s/vivian/sky/g 替换当前行所有 vivian 为 sky

:n,$s/vivian/sky/ 替换第 n 行开始到最后一行中每一行的第一个 vivian 为 sky
:n,$s/vivian/sky/g 替换第 n 行开始到最后一行中每一行所有 vivian 为 sky
n 为数字，若 n 为 .，表示从当前行开始到最后一行

:%s/vivian/sky/（等同于 :g/vivian/s//sky/） 替换每一行的第一个 vivian 为 sky
:%s/vivian/sky/g（等同于 :g/vivian/s//sky/g） 替换每一行中所有 vivian 为 sky

可以使用 # 作为分隔符，此时中间出现的 / 不会作为分隔符
:s#vivian/#sky/# 替换当前行第一个 vivian/ 为 sky/

       I have encountered this kind of situation several times, so I want to find a way to resolve it. With google I find several useful windows command which I did not familiarize.

msg.exe: Send a message to a user local or remote. This is command is used frequently.
       msg username [/SERVER:servername] message
       Send message to username on servername

qprocess.exe: Display information about processes local or remote = query process
       qprocess username [/SERVER:servername]
       Display all processes beloned to username on servername

query.exe: Query TERMSERVER user process and sessions

quser.exe: Display information about a user logged on = query user

tsdiscon.exe: Disconnect a user from a terminal session
       TSDISCON [sessionid | sessionname] [/SERVER:servername] [/V]

tskill.exe: Kill a Terminal server process
       TSKILL processid | processname [/SERVER:servername] [/ID:sessionid | /A] [/V]

logoff.exe: Log user off
       LOGOFF [sessionname | sessionid] [/SERVER:servername] [/V]

       All the commands have an optional  parameter: /SERVER:servername. It is useful to operate other server.

       Lilina 安装挺简单，配置好 conf.php 文件，由于要对 .***.data 文件 和 cache 目录写入，对他们授予适当的权限，然后就可以使用 edit.php 添加 rss 了。我按照 CNOUG.net 的样子修改了导航条，然后是 css 的修改，以让界面和我的站点协调。对 css 还是不太熟悉，这里的调整花费了大量的时间。现在基本完工，还有几个问题需要以后再修改：

1.时区问题：Lilina 没有提供修改时区的功能，现在输出的时间都不对，我看了下 CNOUG.net 也是如此，暂时不管这个问题了。
2.图标问题：经过 anysql 的修改，dreamhost 上已经可以显示图标，但是没有图标的站点会显示一个空白，不太好看，想先用一个默认图标代替它。
3.无法添加 rss：Lilina 似乎对 rss 格式要求非常严格，一些不太符合规范的 rss 怎么也加不进去，暂时只能放弃了。
4.界面还需再调整。

       再花时间去修改也不知道是什么时候的事情了，先将就着用吧，哈哈，看上去还不错。