Oracle11g温习-第十章：存储架构

2013年4月27日星期六

10:38

1、oracle 存储架构：

1) database ------------tablespace-------------segment（对象) ------------extent----------data block

tablespace------------ datafiles ----------------------------------data block

2、oralce segment（段对象) 的类型

1) table segment ---------建立table时，表有记在存储数据时，记录在写入数据块时候，是随机的无序的，访问采用全表扫描。

2) partition table--------对大的table（>2G) 进行分区，减少资源竞争，提高访问速度。

3) cluster(簇) -------------------用于优化表与表的连接查询(用于表与表之间主外键连接查询，加快读取速度)

4) index-------------------提高表的访问速度

5) index organized table（IOT) -------------用于以主键方式建立索引的表，将表中的数据和索引表的数据放在一起提高访问速度。

3、存储空间分配：以extent 为最小单位（extent 由data block 组成)

4、data block

oracle 10g 标准块：8k，支持2~32k

有block header 、free space 、data 组成

数据块并发访问：由数据块的事务槽来分配

initrans ：初始化事务槽的个数（1·255) ，表默认1,index 默认为2；

maxtrans：最大的事务槽个数（默认255)

pctfree：预留给update 操作的空间，free space 大于pctfree 可以insert，小于，不允许insert

5、数据块的free space 管理

1) 手动：在数据字典上建立free list

2) 自动：在本地管理的表空间，通过bitmap来管理data block 的free space（oracle 10g 默认，除了临时、undo表空间)

SYS @ prod >select tablespace_name,contents ,extent_management “ext_man”,segment_space_management “seg_man” from dba_tablespaces;

TABLESPACE_NAME CONTENTS EXT_MAN SEG_MAN

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

SYSTEM PERMANENT LOCAL MANUAL

UNDOTBS1 UNDO LOCAL MANUAL

SYSAUX PERMANENT LOCAL AUTO

TEMP TEMPORARY LOCAL MANUAL

USERS PERMANENT LOCAL AUTO

TEST PERMANENT LOCAL AUTO

6、建立对象的存储信息：

SQL> create table test (id int) tablespace users;

SQL> insert into test values (1) ;

SQL> insert into test values (2) ;

SQL> insert into test values (3) ;

SQL> commit;

SYS@ prod>desc user_segments;

Name Null? Type

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

SEGMENT_NAME VARCHAR2(81)

PARTITION_NAME VARCHAR2(30)

SEGMENT_TYPE VARCHAR2(18)

TABLESPACE_NAME VARCHAR2(30)

BYTES NUMBER

BLOCKS NUMBER

EXTENTS NUMBER

INITIAL_EXTENT NUMBER

NEXT_EXTENT NUMBER

MIN_EXTENTS NUMBER

MAX_EXTENTS NUMBER

PCT_INCREASE NUMBER

FREELISTS NUMBER

FREELIST_GROUPS NUMBER

BUFFER_POOL VARCHAR2(7)

SYS@ prod>select SEGMENT_NAME,SEGMENT_TYPE ,TABLESPACE_NAME,bytes/1024/1024,BLOCKS,extents ,initial_extent/1024/1024 from user_segments where segment_name='TEST';

SEGMENT_NAME SEGMENT_TYPE TABLESPACE BYTES/1024/1024 BLOCKS EXTENTS INITIAL_EXTENT/1024/1024

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

TEST TABLE USERS .0625 8 1 .0625

SQL> select TABLESPACE_NAME ,INITIAL_EXTENT/1024/1024 ,NEXT_EXTENT/1024/1024, EXTENT_MANAGEMENT from dba_tablespaces where TABLESPACE_NAME='USERS';

TABLESPACE_NAME INITIAL_EXTENT/1024/1024 NEXT_EXTENT/1024/1024 EXTENT_MANAGEME

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

USERS .0625 LOCAL

-----------建立对象如果没有指定存储参数，则继承tablespace 的存储参数，test表分配了一个区，大小为4m

SQL> select segment_name,segment_type,TABLESPACE_NAME,EXTENT_ID,bytes/1024/1024,blocks from user_extents where segment_name='TEST';

SEGMENT_NAME SEGMENT_TYPE TABLESPACE_NAME EXTENT_ID BYTES/1024/1024 BLOCKS

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

TEST TABLE USERS 0 4 512

--------------EXTENT_ID 为extent的id号，从0 开始

SQL> select table_name, TABLESPACE_NAME ,PCT_FREE,INI_TRANS ,MAX_TRANS,NUM_ROWS,BLOCKS,EMPTY_BLOCKS from user_tables where table_name='TEST';

TABLE_NAME TABLESPACE_NAME PCT_FREE INI_TRANS MAX_TRANS NUM_ROWS BLOCKS EMPTY_BLOCKS

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

TEST USERS 10 1 255

SQL> analyze table test compute statistics;

Table analyzed.

----------对test 表进行分析，oracle通过分析的信息来建立计划进行优化

SQL> select table_name, TABLESPACE_NAME ,PCT_FREE,INI_TRANS ,MAX_TRANS,NUM_ROWS,BLOCKS,EMPTY_BLOCKS from user_tables

where table_name='TEST';

TABLE_NAME TABLESPACE_NAME PCT_FREE INI_TRANS MAX_TRANS NUM_ROWS BLOCKS EMPTY_BLOCKS

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

TEST USERS 10 1 255 3 54 458

---------------blocks 代表已经使用过的块，empty_blocks 代表从未使用过的块

【HWM :High water Market 高水位线，在segment用来区分已经使用的块和从未使用的块（在做全表扫描时，会一直扫描到HWM) 】

SQL> begin

for i in 4..100000 loop

insert into test values (i) ;

end loop;

end;

SQL> analyze table test compute statistics;

Table analyzed.

SQL> select table_name, TABLESPACE_NAME ,PCT_FREE,INI_TRANS ,MAX_TRANS,NUM_ROWS,BLOCKS,EMPTY_BLOCKS from user_tables

where table_name='TEST';

TABLE_NAME TABLESPACE_NAME PCT_FREE INI_TRANS MAX_TRANS NUM_ROWS BLOCKS EMPTY_BLOCKS

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

TEST USERS 10 1 255 100000 182 330

建立autotrace ，跟踪sql语句

SQL> conn /as sysdba

Connected.

SQL> @?/rdbms/admin/catplan.sql;

创建PLUSTRACE 角色

SQL> conn /as sysdba

SQL> @ ?/sqlplus/admin/plustrce.sql

SQL> grant plustrace to public

源文档 <http://www.itpub.net/forum.php?mod=viewthread&tid=1747729>

set autotrace on 打开自动跟踪

set autotrace off 关闭自动跟踪

set autotrace traceonly 只显示trace 信息，不显示对象的记录信息

------------对test 做全表扫描

SQL> set autotrace traceonly;

SQL> select * from test;

Execution Plan

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

Plan hash value: 1357081020

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

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

| 0 | SELECT STATEMENT | | 100K| 390K| 49 (15) | 00:00:01 |

| 1 | TABLE ACCESS FULL| TEST | 100K| 390K| 49 (15) | 00:00:01 |

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

Statistics

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

1 recursive calls

0 db block gets

6851 consistent gets

0 physical reads

0 redo size

1855907 bytes sent via SQL*Net to client

73710 bytes received via SQL*Net from client

6668 SQL*Net roundtrips to/from client

0 sorts (memory)

0 sorts (disk)

100000 rows processed

SQL> delete from test;

delete from test

ERROR at line 1:

【ORA-30036: unable to extend segment by 8 in undo tablespace 'UNDO_TBS01'】

---------undo 表空间太小，不能 auto extend

SQL> /

FILE_NAME FILE_ID TABLESPACE_NAME

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

/u01/app/oracle/oradata/lx02/system01.dbf 1 SYSTEM

/u01/app/oracle/oradata/lx02/lx02.dbf 11 LX02

/u01/app/oracle/oradata/lx02/OLTP01.DBF 7 OLTP

/u01/app/oracle/oradata/lx02/indx01.dbf 6 INDX

/u01/app/oracle/oradata/lx02/example01.dbf 5 EXAMPLE

/u01/app/oracle/oradata/lx02/user01.dbf 4 USERS

/u01/app/oracle/oradata/lx02/sysaux01.dbf 3 SYSAUX

/u01/app/oracle/oradata/lx02/rtbs01.dbf 2 RTBS

/u01/app/oracle/oradata/lx02/test01.dbf 8 TEST

/u01/app/oracle/oradata/tbs16k01.dbf 9 TBS_16K

/u01/app/oracle/oradata/lx02/lx01.dbf 10 LX01

/u01/app/oracle/oradata/lx02/undotbs01.dbf 12 UNDO_TBS01

/u01/app/oracle/oradata/lx02/test02.dbf 13 TEST

/u01/app/oracle/oradata/bigtbs01.dbf 14 BIG_TBS

SQL> alter database datafile 12 autoextend on next 10m maxsize 500m;

Database altered.

-----------undo tablespace自动扩展

SQL> delete from test;

100000 rows deleted.

SQL> set autotrace off

SQL> select table_name, TABLESPACE_NAME ,PCT_FREE,INI_TRANS ,MAX_TRANS,NUM_ROWS,BLOCKS,EMPTY_BLOCKS from user_tables

where table_name='TEST';

TABLE_NAME TABLESPACE_NAME PCT_FREE INI_TRANS MAX_TRANS NUM_ROWS BLOCKS EMPTY_BLOCKS

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

TEST USERS 10 1 255 0 182 330

----------【delete 删除数据 不会重置高水位 没有释放占用的数据块

Truncate 删除数据 并且重置高水位 释放占用的数据块】

SQL> insert into test values (1) ;

SQL> insert into test values (2) ;

SQL> commit;

SQL> set autotrace on;

SQL> select * from test;

----------

Execution Plan

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

Execution Plan

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

Plan hash value: 1357081020

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

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

| 0 | SELECT STATEMENT | | 2 | 26 | 2 (0) | 00:00:01 |

| 1 | TABLE ACCESS FULL| TEST | 2 | 26 | 2 (0) | 00:00:01 |

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

Note

-----

- dynamic sampling used for this statement

Statistics

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

28 recursive calls

0 db block gets

10 consistent gets

0 physical reads

0 redo size

451 bytes sent via SQL*Net to client

385 bytes received via SQL*Net from client

2 SQL*Net roundtrips to/from client

0 sorts (memory)

0 sorts (disk)

2 rows processed

---------【delete 不释放已经使用的块，所以两行记录在做全表扫描的时候也要访问所有已经使用过的块（扫描到HWM) 】

SQL> set autotrace off

SQL> truncate table test;

Table truncated.

SQL> analyze table test compute statistics;

SQL> select table_name, TABLESPACE_NAME ,PCT_FREE,INI_TRANS ,MAX_TRANS,NUM_ROWS,BLOCKS,EMPTY_BLOCKS from user_tables

where table_name='TEST';

TABLE_NAME TABLESPACE_NAME PCT_FREE INI_TRANS MAX_TRANS NUM_ROWS BLOCKS EMPTY_BLOCKS

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

TEST USERS 10 1 255 0 0 512

SQL> insert into test values (1) ;

SQL> insert into test values (2) ;

SQL> commit;

SQL> analyze table test compute statistics;

Table analyzed.

SQL> select table_name, TABLESPACE_NAME ,PCT_FREE,INI_TRANS ,MAX_TRANS,NUM_ROWS,BLOCKS,EMPTY_BLOCKS from user_tables

where table_name='TEST';

TABLE_NAME TABLESPACE_NAME PCT_FREE INI_TRANS MAX_TRANS NUM_ROWS BLOCKS EMPTY_BLOCKS

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

TEST USERS 10 1 255 2 54 458

SQL> set autotrace on

SQL> select * from test;

----------

Execution Plan

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

Plan hash value: 1357081020

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

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

| 0 | SELECT STATEMENT | | 2 | 4 | 2 (0) | 00:00:01 |

| 1 | TABLE ACCESS FULL| TEST | 2 | 4 | 2 (0) | 00:00:01 |

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

Statistics

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

1 recursive calls

0 db block gets

4 consistent gets

0 physical reads

0 redo size

451 bytes sent via SQL*Net to client

385 bytes received via SQL*Net from client

2 SQL*Net roundtrips to/from client

0 sorts (memory)

0 sorts (disk)

2 rows processed

------------【truncate操作会释放该对象的存储空间的高水位线】

SQL> create table t01 (id int)

pctfree 20 pctused 40 initrans 3

storage( initial 128k next 1m pctincrease 50) ;

Table created.

SQL> select table_name,TABLESPACE_NAME,PCT_FREE,PCT_USED ,INI_TRANS,INITIAL_EXTENT/1024,NEXT_EXTENT/1024/1024,PCT_INCREASE from user_tables

where table_name='T01';

TABLE_NAME TABLESPACE_NAME PCT_FREE PCT_USED INI_TRANS INITIAL_EXTENT/1024 NEXT_EXTENT/1024/1024 PCT_INCREASE

------------------------------ ------------------------------ ---------- ---------- ---------- ------------------- --------------------- --------------------------------- -----------------T01 USERS 20 3 128 4 0

---------在local 管理的表空间上，存储参数设置意义不大

SQL> select owner, SEGMENT_NAME,TABLESPACE_NAME, BYTES from dba_segments

where owner='SCOTT';

OWNER SEGMENT_NAME TABLESPACE_NAME BYTES

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

SCOTT DEPT USERS 4194304

SCOTT PK_DEPT USERS 4194304

SCOTT EMP USERS 4194304

SCOTT PK_EMP USERS 4194304

SCOTT BONUS USERS 4194304

SCOTT SALGRADE USERS 4194304

SCOTT TEST USERS 4194304

SCOTT T01 USERS 4194304

8 rows selected.

【delete 删除数据 不会重置高水位 不会释放占用的数据块】【Truncate 删除数据 并且重置高水位 释放占用的数据块】

Execution Plan Execution Plan

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

Plan hash value: 1357081020 Plan hash value: 1357081020

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

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

| 0 | SELECT STATEMENT | | 1 | 13 | 43 (3)| 00:00:01 | | 0 | SELECT STATEMENT | | 1 | 13 | 2 (0)| 00:00:01 |

| 1 | TABLE ACCESS FULL| TEST | 1 | 13 | 43 (3)| 00:00:01 | | 1 | TABLE ACCESS FULL| TEST | 1 | 13 | 2 (0)| 00:00:01 |

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

Execution Plan Execution Plan

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

Plan hash value: 1357081020 Plan hash value: 1357081020

Statistics Statistics

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

1 recursive calls 1 recursive calls

0 db block gets 0 db block gets

185 consistent gets 22 consistent gets

0 physical reads 0 physical reads

0 redo size 0 redo size

451 bytes sent via SQL*Net to client 451 bytes sent via SQL*Net to client

384 bytes received via SQL*Net from client 384 bytes received via SQL*Net from client

2 SQL*Net roundtrips to/from client 2 SQL*Net roundtrips to/from client

0 sorts (memory) 0 sorts (memory)

0 sorts (disk) 0 sorts (disk)

2 rows processed 2 rows processed

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原文地址：https://www.cnblogs.com/iyoume2008/p/7525281.html