月归档：十二月 2012

ORCLE 12C 增加列,无默认值

发表于 2012 年 12 月 19 日由惜分飞

对11gR2比较熟悉的朋友应该比较清楚,在该版本中引入了一个新的特性,能够快速的增加一个新列,具体见Oracle 11g增加列,并带默认值的新特性,但是这个功能在该版本中总有个不足,需要设置默认值,在有些情况下,有些列就是不需要默认值,在12C的版本中,解决了这个鸡肋,能够快速增加一个列而且可以是不指定默认值(默认值为NULL)
数据库12C版本

SQL> select * from v$version;

BANNER                                                                               CON_ID
-------------------------------------------------------------------------------- ----------
Oracle Database 12c Enterprise Edition Release 12.1.0.0.2 - 64bit                         0
PL/SQL Release 12.1.0.0.2                                                                 0
CORE    12.1.0.0.2                                                                        0
TNS for Linux: Version 12.1.0.0.2                                                         0
NLSRTL Version 12.1.0.0.2                                                                 0

创建模拟表

SQL> create table t_xifenfei(id number,name varchar2(20));

Table created.

SQL> desc t_xifenfei
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 ID                                                 NUMBER
 NAME                                               VARCHAR2(20)

SQL> insert into t_xifenfei values (1,'www.xifenfei.com');

1 row created.

SQL> insert into t_xifenfei values (2,'www.xifenfei.com');

1 row created.

SQL> insert into t_xifenfei values (3,'www.xifenfei.com');

1 row created.

SQL> commit;

Commit complete.

SQL> select * from t_xifenfei;

        ID NAME
---------- --------------------
         1 www.xifenfei.com
         2 www.xifenfei.com
         3 www.xifenfei.com

第一次dump block

SQL> select   rowid, 
  2   dbms_rowid.rowid_relative_fno(rowid)rel_fno,
  3   dbms_rowid.rowid_block_number(rowid)blockno,
  4   dbms_rowid.rowid_row_number(rowid) rowno
  5   from t_xifenfei ;

ROWID                 REL_FNO    BLOCKNO      ROWNO
------------------ ---------- ---------- ----------
AAAEy3AAEAAAAGGAAA          4        390          0
AAAEy3AAEAAAAGGAAB          4        390          1
AAAEy3AAEAAAAGGAAC          4        390          2

SQL> alter system dump datafile 4 block 390;

System altered.

--dump block 
block_row_dump:
tab 0, row 0, @0x1f81
tl: 23 fb: --H-FL-- lb: 0x1  cc: 2
col  0: [ 2]  c1 02
col  1: [16]  77 77 77 2e 78 69 66 65 6e 66 65 69 2e 63 6f 6d
tab 0, row 1, @0x1f6a
tl: 23 fb: --H-FL-- lb: 0x1  cc: 2
col  0: [ 2]  c1 03
col  1: [16]  77 77 77 2e 78 69 66 65 6e 66 65 69 2e 63 6f 6d
tab 0, row 2, @0x1f53
tl: 23 fb: --H-FL-- lb: 0x1  cc: 2
col  0: [ 2]  c1 04
col  1: [16]  77 77 77 2e 78 69 66 65 6e 66 65 69 2e 63 6f 6d
end_of_block_dump

增加不含默认值列

SQL> alter table t_xifenfei add c_xff varchar2(100);

Table altered.

SQL> desc t_xifenfei
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 ID                                                 NUMBER
 NAME                                               VARCHAR2(20)
 C_XFF                                              VARCHAR2(100)
--证明增加列无默认值

SQL> insert into t_xifenfei values(4,'www.xifenfei.com','www.orasos.com');

1 row created.

SQL> commit;

Commit complete.

第二次dump block

SQL> alter system checkpoint;

System altered.

SQL>  alter system dump datafile 4 block 390;

System altered.

--block dump 
block_row_dump:
tab 0, row 0, @0x1f81
tl: 23 fb: --H-FL-- lb: 0x1  cc: 2
col  0: [ 2]  c1 02
col  1: [16]  77 77 77 2e 78 69 66 65 6e 66 65 69 2e 63 6f 6d
tab 0, row 1, @0x1f6a
tl: 23 fb: --H-FL-- lb: 0x1  cc: 2
col  0: [ 2]  c1 03
col  1: [16]  77 77 77 2e 78 69 66 65 6e 66 65 69 2e 63 6f 6d
tab 0, row 2, @0x1f53
tl: 23 fb: --H-FL-- lb: 0x1  cc: 2
col  0: [ 2]  c1 04
col  1: [16]  77 77 77 2e 78 69 66 65 6e 66 65 69 2e 63 6f 6d
tab 0, row 3, @0x1f2d
tl: 38 fb: --H-FL-- lb: 0x2  cc: 3
col  0: [ 2]  c1 05
col  1: [16]  77 77 77 2e 78 69 66 65 6e 66 65 69 2e 63 6f 6d
col  2: [14]  77 77 77 2e 6f 72 61 73 6f 73 2e 63 6f 6d
end_of_block_dump

从这里可以明显的看出来,前面的三条记录只有2列,但是四条记录有3列,证明使用了11gR2的新特性,这里可以使用null的默认值,证明比以往版本新特性增强.

发表在 ORACLE 12C | 标签为 ORACLE 12C | 一条评论

ORACLE 12C Invisible Columns and Column Ordering

发表于 2012 年 12 月 16 日由惜分飞

在ORACLE 12C中有了Invisible Columns的概念,就是在表中真实的存在该列,但是通过设置Invisible导致该列不可显示.官方说明:

The property of whether a column is visible can be controlled by the user. 
Invisible columns are not seen unless specified explicitly in the SELECT list.
Any generic access of a table (such as a SELECT * FROM table or a DESCRIBE) 
  will not show invisible columns.

数据库版本

SQL> select * from v$version;

BANNER                                                                               CON_ID
-------------------------------------------------------------------------------- ----------
Oracle Database 12c Enterprise Edition Release 12.1.0.0.2 - 64bit                         0
PL/SQL Release 12.1.0.0.2                                                                 0
CORE    12.1.0.0.2                                                                        0
TNS for Linux: Version 12.1.0.0.2                                                         0
NLSRTL Version 12.1.0.0.2                                                                 0

创建含INVISIBLE列表

SQL> CREATE TABLE t_xifenfei (a number, b number INVISIBLE, c number);

Table created.

SQL> desc t_xifenfei
 Name                                                  Null?    Type
 ----------------------------------------------------- -------- ---------------------------
 A                                                              NUMBER
 C                                                              NUMBER

SQL>  select column_name,HIDDEN_COLUMN,COLUMN_ID from user_TAB_COLs  where TABLE_NAME='T_XIFENFEI';

COLUMN_NAM HID  COLUMN_ID
---------- --- ----------
A          NO           1
B          YES
C          NO           2

通过观察可以发现INVISIBLE列在一般的查询中不显示,在USER_TAB_COLS的视图中显示:HIDDEN_COLUMN为YES而且COLUMN_ID为空

设置INVISIBLE列为VISIBLE

SQL> ALTER TABLE t_xifenfei MODIFY (b VISIBLE);

Table altered.

SQL> desc t_xifenfei
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 A                                                  NUMBER
 C                                                  NUMBER
 B                                                  NUMBER

SQL> select column_name,HIDDEN_COLUMN,COLUMN_ID from user_TAB_COLs  where TABLE_NAME='T_XIFENFEI';

COLUMN_NAM HID  COLUMN_ID
---------- --- ----------
A          NO           1
B          NO           3
C          NO           2

当设置为VISIBLE时HIDDEN_COLUMN为YES而且COLUMN_ID为递增值

修改列展示顺序(Column Ordering)

SQL> ALTER TABLE t_xifenfei MODIFY (a invisible);

Table altered.

SQL> ALTER TABLE t_xifenfei MODIFY (a visible);

Table altered.

SQL> desc t_xifenfei
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 C                                                  NUMBER
 B                                                  NUMBER
 A                                                  NUMBER

SQL> select column_name,HIDDEN_COLUMN,COLUMN_ID from user_TAB_COLs  where TABLE_NAME='T_XIFENFEI';

COLUMN_NAM HID  COLUMN_ID
---------- --- ----------
A          NO           3
B          NO           2
C          NO           1

通过INVISIBLE和VISIBLE相关操作,实现A列从头移尾,实现列的Column Ordering效果.
补充说明:在以前的blog中,提供了修改col$基表的方法(通过修改col$.col#改变列展示顺序)来实现列的顺序修改,相对于这种方法来说,修改数据字典的方法风险太大,需要非常谨慎,而且不被ORACLE SUPPORT

发表在 ORACLE 12C | 标签为 ORACLE 12C | 3 条评论

ORACLE 12C 支持multiple partitions同时操作

发表于 2012 年 12 月 15 日由惜分飞

ORACLE 12C在分区维护方面有了不少的增强,在12C的beta版本中已经支持多分区的add/truncate/drop/merge操作,大大的提高了分区维护的效率.
数据库版本

SQL> select * from v$version;

BANNER                                                                               CON_ID
-------------------------------------------------------------------------------- ----------
Oracle Database 12c Enterprise Edition Release 12.1.0.0.2 - 64bit                         0
PL/SQL Release 12.1.0.0.2                                                                 0
CORE    12.1.0.0.2                                                                        0
TNS for Linux: Version 12.1.0.0.2                                                         0
NLSRTL Version 12.1.0.0.2                                                                 0

在FF PDB中创建xff用户

SQL> alter session set container=ff;

Session altered.

SQL> create user xff identified by xifenfei;

User created.

SQL> grant dba to xff;

Grant succeeded.

SQL> conn xff/xifenfei@ff
Connected.
SQL> show con_name;

CON_NAME
------------------------------
FF

创建分区表RANGE PARTITIONS

SQL> CREATE TABLE t_xifenfei
  2  (name varchar2(100),time_id DATE)
  3  partition by range(time_id)
  4  (partition xff_2006 values less than (TO_DATE('01-01-2007','dd-MM-yyyy')),
  5  partition xff_2007 values less than (TO_DATE('01-01-2008','dd-MM-yyyy')),
  6  partition xff_2008 values less than (TO_DATE('01-01-2009','dd-MM-yyyy')),
  7  partition xff_2009 values less than (TO_DATE('01-01-2010','dd-MM-yyyy')));

Table created.

SQL> SET LONG 30
SQL> select PARTITION_NAME,HIGH_VALUE FROM USER_TAB_PARTITIONS where table_name='T_XIFENFEI';

PARTITION_NAME                 HIGH_VALUE
------------------------------ ------------------------------
XFF_2006                       TO_DATE(' 2007-01-01 00:00:00'
XFF_2007                       TO_DATE(' 2008-01-01 00:00:00'
XFF_2008                       TO_DATE(' 2009-01-01 00:00:00'
XFF_2009                       TO_DATE(' 2010-01-01 00:00:00'

ADD 多个分区

SQL> ALTER TABLE t_xifenfei ADD 
  2    PARTITION XFF_2010 VALUES LESS THAN (TO_DATE('01-01-2011','dd-MM-yyyy')),
  3    PARTITION XFF_2011 VALUES LESS THAN (TO_DATE('01-01-2012','dd-MM-yyyy')),
  4    PARTITION XFF_2012 VALUES LESS THAN (TO_DATE('01-01-2013','dd-MM-yyyy'));

Table altered.

SQL> select PARTITION_NAME,HIGH_VALUE FROM USER_TAB_PARTITIONS where table_name='T_XIFENFEI';

PARTITION_NAME                 HIGH_VALUE
------------------------------ ------------------------------
XFF_2006                       TO_DATE(' 2007-01-01 00:00:00'
XFF_2007                       TO_DATE(' 2008-01-01 00:00:00'
XFF_2008                       TO_DATE(' 2009-01-01 00:00:00'
XFF_2009                       TO_DATE(' 2010-01-01 00:00:00'
XFF_2010                       TO_DATE(' 2011-01-01 00:00:00'
XFF_2011                       TO_DATE(' 2012-01-01 00:00:00'
XFF_2012                       TO_DATE(' 2013-01-01 00:00:00'

7 rows selected.

Split多个分区

SQL> ALTER TABLE t_xifenfei  split PARTITION  XFF_2012 INTO
  2    (PARTITION XFF_2012_03 VALUES LESS THAN (TO_DATE('01-03-2012','dd-MM-yyyy')),
  3    PARTITION XFF_2012_06 VALUES LESS THAN (TO_DATE('01-06-2012','dd-MM-yyyy')),
  4    PARTITION XFF_2012_09 VALUES LESS THAN (TO_DATE('01-09-2012','dd-MM-yyyy')),
  5    PARTITION XFF_2012);

Table altered.

SQL>  select PARTITION_NAME,HIGH_VALUE FROM USER_TAB_PARTITIONS where table_name='T_XIFENFEI';

PARTITION_NAME                 HIGH_VALUE
------------------------------ ------------------------------
XFF_2006                       TO_DATE(' 2007-01-01 00:00:00'
XFF_2007                       TO_DATE(' 2008-01-01 00:00:00'
XFF_2008                       TO_DATE(' 2009-01-01 00:00:00'
XFF_2009                       TO_DATE(' 2010-01-01 00:00:00'
XFF_2010                       TO_DATE(' 2011-01-01 00:00:00'
XFF_2011                       TO_DATE(' 2012-01-01 00:00:00'
XFF_2012                       TO_DATE(' 2013-01-01 00:00:00'
XFF_2012_03                    TO_DATE(' 2012-03-01 00:00:00'
XFF_2012_06                    TO_DATE(' 2012-06-01 00:00:00'
XFF_2012_09                    TO_DATE(' 2012-09-01 00:00:00'

10 rows selected.

插入分区数据

SQL>INSERT INTO t_xifenfei VALUES('www.xifenfei.com',SYSDATE-100);

1 row created.

SQL> INSERT INTO t_xifenfei VALUES('www.xifenfei.com',SYSDATE-200);

1 row created.

SQL> INSERT INTO t_xifenfei VALUES('www.xifenfei.com',SYSDATE-300);

1 row created.

SQL>  INSERT INTO t_xifenfei VALUES('www.xifenfei.com',SYSDATE-10);

1 row created.

SQL> commit;

Commit complete.

SQL> col name for a20
SQL> select * from t_xifenfei;

NAME                 TIME_ID
-------------------- ---------
www.xifenfei.com     17-FEB-12
www.xifenfei.com     27-MAY-12
www.xifenfei.com     04-SEP-12
www.xifenfei.com     03-DEC-12

SQL>select * from t_xifenfei PARTITION(XFF_2012_03);

NAME                 TIME_ID
-------------------- ---------
www.xifenfei.com     17-FEB-12

SQL> select * from t_xifenfei PARTITION(XFF_2012_06);

NAME                 TIME_ID
-------------------- ---------
www.xifenfei.com     27-MAY-12

SQL>  select * from t_xifenfei PARTITION(XFF_2012_09);

no rows selected

SQL>  select * from t_xifenfei PARTITION(XFF_2012);

NAME                 TIME_ID
-------------------- ---------
www.xifenfei.com     04-SEP-12
www.xifenfei.com     03-DEC-12

TRUNCATE 多个分区

SQL> Alter table t_xifenfei truncate partitions XFF_2012_03, XFF_2012_06, XFF_2012_09;

Table truncated.

--剩下两条记录存在于XFF_2012中
SQL> select * from t_xifenfei;

NAME                 TIME_ID
-------------------- ---------
www.xifenfei.com     04-SEP-12
www.xifenfei.com     03-DEC-12

SQL> SELECT SUBOBJECT_NAME,object_id,data_object_id from user_objects where SUBOBJECT_NAME like 'XFF_2012_0%';

SUBOBJECT_NAME                  OBJECT_ID DATA_OBJECT_ID
------------------------------ ---------- --------------
XFF_2012_09                         90603          90603    <---为什么没有变
XFF_2012_06                         90602          90606
XFF_2012_03                         90601          90605

SQL> select PARTITION_NAME,HIGH_VALUE,SEGMENT_CREATED FROM USER_TAB_PARTITIONS where table_name='T_XIFENFEI';

PARTITION_NAME                 HIGH_VALUE                     SEGM
------------------------------ ------------------------------ ----
XFF_2006                       TO_DATE(' 2007-01-01 00:00:00' NO
XFF_2007                       TO_DATE(' 2008-01-01 00:00:00' NO
XFF_2008                       TO_DATE(' 2009-01-01 00:00:00' NO
XFF_2009                       TO_DATE(' 2010-01-01 00:00:00' NO
XFF_2010                       TO_DATE(' 2011-01-01 00:00:00' NO
XFF_2011                       TO_DATE(' 2012-01-01 00:00:00' NO
XFF_2012                       TO_DATE(' 2013-01-01 00:00:00' YES
XFF_2012_03                    TO_DATE(' 2012-03-01 00:00:00' YES
XFF_2012_06                    TO_DATE(' 2012-06-01 00:00:00' YES
XFF_2012_09                    TO_DATE(' 2012-09-01 00:00:00' NO  
--XFF_2012_09因为块延迟创建,没有segment导致truncate对应的dataobj#不变

10 rows selected.

DROP 多个分区

SQL>  Alter table t_xifenfei DROP  partitions XFF_2012_03, XFF_2012_06, XFF_2012_09;

Table altered.

SQL> select PARTITION_NAME,HIGH_VALUE FROM USER_TAB_PARTITIONS where table_name='T_XIFENFEI';

PARTITION_NAME                 HIGH_VALUE
------------------------------ ------------------------------
XFF_2006                       TO_DATE(' 2007-01-01 00:00:00'
XFF_2007                       TO_DATE(' 2008-01-01 00:00:00'
XFF_2008                       TO_DATE(' 2009-01-01 00:00:00'
XFF_2009                       TO_DATE(' 2010-01-01 00:00:00'
XFF_2010                       TO_DATE(' 2011-01-01 00:00:00'
XFF_2011                       TO_DATE(' 2012-01-01 00:00:00'
XFF_2012                       TO_DATE(' 2013-01-01 00:00:00'

7 rows selected.

MERGE 多分区

SQL> Alter table t_xifenfei merge partitions XFF_2006, XFF_2007, XFF_2008 into partition XFF_OLD;

Table altered.

SQL> select PARTITION_NAME,HIGH_VALUE FROM USER_TAB_PARTITIONS where table_name='T_XIFENFEI';

PARTITION_NAME                 HIGH_VALUE
------------------------------ ------------------------------
XFF_2009                       TO_DATE(' 2010-01-01 00:00:00'
XFF_2010                       TO_DATE(' 2011-01-01 00:00:00'
XFF_2011                       TO_DATE(' 2012-01-01 00:00:00'
XFF_2012                       TO_DATE(' 2013-01-01 00:00:00'
XFF_OLD                        TO_DATE(' 2009-01-01 00:00:00'

本测试是基于Range partitions进行,其实在ORACLE 12C中对于分区表的维护做了比较大的增强,上面试验的多分区操作,也支持List partitions和subpartitions.ddl一次性操作多个分区,给分区经常做维护的DBA来说,带来了不少的方便,省去了很多重复行工作.

发表在 ORACLE 12C | 标签为 ORACLE 12C | 评论关闭

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月归档：十二月 2012

ORCLE 12C 增加列,无默认值

ORACLE 12C Invisible Columns and Column Ordering

ORACLE 12C 支持multiple partitions同时操作

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月归档：十二月 2012

ORCLE 12C 增加列,无默认值

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ORACLE 12C 支持multiple partitions同时操作

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