ORACLE 10g append跟nologging插入对REDO的影响

1.  append 属于direct insert,归档模式下append+table nologging会大量减少日志,

    非归档模式append会大量减少日志,append方式插入只会产生很少的undo

2.

综合一下吧：一是减少对空间的搜索；二是有可能减少redolog的产生。所以append方式会快很多，一般用于大数据量的处理 3. 建议不要经常使用append，这样表空间会一直在高水位上，除非你这个表只插不删 4.

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oracle append有什么作用？

请教一下，oracle中append是做什么用的。

  insert into table1 select * from table2

在使用了append选项以后，insert数据会直接加到表的最后面，而不会在表的空闲块中插入数据。

使用append会增加数据插入的速度。 的作用是在表的高水位上分配空间,不再使用表的extent中的空余空间

append 属于direct insert,归档模式下append+table nologging会大量减少日志,非归档模式append会大量减少日志,append方式插入只会产生很少的undo 不去寻找 freelist 中的free block , 直接在table HWM 上面加入数据。

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SQL> select * from v$version;

BANNER

----------------------------------------------------------------

Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Prod

PL/SQL Release 10.2.0.1.0 - Production

CORE    10.2.0.1.0      Production

TNS for 32-bit Windows: Version 10.2.0.1.0 - Production

NLSRTL Version 10.2.0.1.0 – Production

1.非归档模式append,nologging,append+nologging 三种情况数据产生REDO的对比

PHP:

SQL> archive log list

Database log mode              No Archive Mode

Automatic archival             Disabled

Archive destination            USE_DB_RECOVERY_FILE_DEST

Oldest online log sequence     13

Current log sequence           15

SQL> create table t as select * from dba_objects where 1=2;

Table created.

SQL> select name,value,class from v$sysstat where name='redo size';

NAME            VALUE      CLASS

---------- ---------- ----------

redo size      582728          2

SQL> insert into t select * from dba_objects;

10947 rows created.

SQL> select name,value,class from v$sysstat where name='redo size';

NAME            VALUE      CLASS

---------- ---------- ----------

redo size     1745704          2

SQL> insert into t select * from dba_objects;

10947 rows created.

SQL> select name,value,class from v$sysstat where name='redo size';

NAME            VALUE      CLASS

---------- ---------- ----------

redo size     1839872          2

SQL> select (1745704-582728) redo1,(1839872-1745704) redo2 from dual;

     REDO1      REDO2

---------- ----------

   1162976     94168

SQL> drop table t;

Table dropped.

SQL> create table t nologging as select * from dba_objects where 1=2;

Table created.

SQL> select name,value,class from v$sysstat where name='redo size';

NAME            VALUE      CLASS

---------- ---------- ----------

redo size     3441836          2

SQL> insert into t select * from dba_objects;

10947 rows created.

SQL> select name,value,class from v$sysstat where name='redo size';

NAME            VALUE      CLASS

---------- ---------- ----------

redo size     4660204          2

SQL> insert into t select * from dba_objects;

10947 rows created.

SQL> select name,value,class from v$sysstat where name='redo size';

NAME            VALUE      CLASS

---------- ---------- ----------

redo size     4667180          2

SQL> select (4660204-3441836) redo1,(4667180-4660204) redo2 from dual;

     REDO1      REDO2

---------- ----------

   1218368       6976

2.归档下:append,nologging,append+nologging 三种情况数据产生REDO的对比

PHP语言:SQL> select flashback_on from v$database;

FLASHBACK_ON

------------------

NO

SQL> archive log list

Database log mode              Archive Mode

Automatic archival             Enabled

Archive destination            USE_DB_RECOVERY_FILE_DEST

Oldest online log sequence     13

Next log sequence to archive   15

Current log sequence           15

SQL> select log_mode from v$database;

LOG_MODE

------------

ARCHIVELOG

SQL> create table t as select * from dba_objects where 1=2;

Table created.

SQL> select name,value from v$sysstat where name='redo size';

NAME            VALUE

---------- ----------

redo size      155624

SQL> insert into t select * from dba_objects;

10947 rows created.

SQL> select name,value from v$sysstat where name='redo size';

NAME            VALUE

---------- ----------

redo size     1316420

SQL> insert into t select * from dba_objects;

10947 rows created.

SQL> select name,value from v$sysstat where name='redo size';

NAME            VALUE

---------- ----------

redo size     2461876

SQL> select (1316420-155624) redo1,(2461876-1316420) redo2 from dual;

     REDO1      REDO2

---------- ----------

   1160796    1145456

SQL> truncate table t;

Table truncated.

SQL> alter table t nologging;

Table altered.

SQL> select name,value from v$sysstat where name='redo size';

NAME            VALUE

---------- ----------

redo size     2505320

SQL> insert into t select * from dba_objects;

10947 rows created.

SQL> select name,value from v$sysstat where name='redo size';

NAME            VALUE

---------- ----------

redo size     3667856

SQL> insert into t select * from dba_objects;

10947 rows created.

SQL> select name,value from v$sysstat where name='redo size';

NAME            VALUE

---------- ----------

redo size     3670424

SQL> select (3667856-2505320) redo1,(3670424-3667856) redo2 from dual;

     REDO1      REDO2

---------- ----------

   1162536       2568

总结:

 normal

 append

 nologging

 Append+nologging

Noarchive

 1162976

 94168

 1218368

 6976

Archive

 1160796

 1145456

 1162536

 2568

可以看出

1. 不管哪种模式下append要与nologging方式联用才能达到很好的效果。

2. 非归档与归档方式，只用NOLOGGING是不起效果的。

3. 非归档下append已达到不错的效果，但不及与nologging的联用方式。

4. 归档下单append起不到效果。

NOLOGGING插完后最好做个备份。

另外，如果库处在FORCELOGGING模式下，此时的nologging方式是无效的，这个我也测试过。

ITPUB上也有关于NOLOGGING何时生效的讨论

http://www.itpub.net/showthread.php?threadid=239905

eygle也做过这个实验

http://www.eygle.com/faq/Nologging&append.htm

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Originally posted by jwzl at 2004-12-6 09:02:

我想确认一下系统到底会不会写日志，

很多人说不写日志，但怎么还有另外一个参数nologing,

如果真的没有写日志，也是很麻烦的

写的日志量不同^_^.

汇总一下下面的例子中关于redo log的信息.

pure insert                587624  

insert with nologging  585496  

insert with append 2240  

insert with append & nologging 400  

[quote]

Connected to:

Oracle9i Enterprise Edition Release 9.2.0.4.0 - Production

With the Partitioning, OLAP and Oracle Data Mining options

JServer Release 9.2.0.4.0 - Production

SQL> drop table t;

Table dropped.

SQL> create table t nologging as select * from dba_objects where null = null;

Table created.

SQL> set autot traceonly stat

SQL> insert into t select * from dba_objects;

5888 rows created.

Statistics

----------------------------------------------------------

        271  recursive calls

        773  db block gets

      12653  consistent gets

          0  physical reads

     587624  redo size

        617  bytes sent via SQL*Net to client

        539  bytes received via SQL*Net from client

          3  SQL*Net roundtrips to/from client

          2  sorts (memory)

          0  sorts (disk)

       5888  rows processed

SQL> insert into t nologging select * from dba_objects;

5888 rows created.

Statistics

----------------------------------------------------------

         28  recursive calls

        721  db block gets

      12654  consistent gets

          0  physical reads

     585496  redo size

        618  bytes sent via SQL*Net to client

        549  bytes received via SQL*Net from client

          3  SQL*Net roundtrips to/from client

          1  sorts (memory)

          0  sorts (disk)

       5888  rows processed

SQL> insert into t select * from dba_objects;

5888 rows created.

Statistics

----------------------------------------------------------

         29  recursive calls

         31  db block gets

      12526  consistent gets

          0  physical reads

       2240  redo size

        603  bytes sent via SQL*Net to client

        551  bytes received via SQL*Net from client

          3  SQL*Net roundtrips to/from client

          1  sorts (memory)

          0  sorts (disk)

       5888  rows processed

SQL> commit;

Commit complete.

SQL> insert into t nologging select * from dba_objects;

5888 rows created.

Statistics

----------------------------------------------------------

          7  recursive calls

          8  db block gets

      12517  consistent gets

          0  physical reads

        400  redo size

        603  bytes sent via SQL*Net to client

        561  bytes received via SQL*Net from client

          3  SQL*Net roundtrips to/from client

          1  sorts (memory)

          0  sorts (disk)

       5888  rows processed

SQL> commit;

Commit complete.

SQL> exit

[/code]