第十章： 存储架构
1、oracle 存储架构：
1） database ------------tablespace-------------segment（对象）------------extent----------data block
tablespace------------ datafiles ----------------------------------data block
2、oralce segment（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，随机的是无序的，访问采用全表扫面。
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-------------------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）
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。
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）
03:32:36 SQL> select tablespace_name,contents ,extent_management,segment_space_management from dba_tablespaces;
TABLESPACE_NAME CONTENTS EXTENT_MAN SEGMEN
------------------------------ --------- ---------- ------
SYSTEM PERMANENT DICTIONARY MANUAL
RTBS UNDO LOCAL MANUAL
SYSAUX PERMANENT LOCAL AUTO
TEMP TEMPORARY LOCAL MANUAL
USERS PERMANENT LOCAL AUTO
EXAMPLE PERMANENT LOCAL AUTO
INDX PERMANENT LOCAL AUTO
OLTP PERMANENT LOCAL AUTO
TEST PERMANENT LOCAL AUTO
LX01 PERMANENT LOCAL AUTO
LX02 PERMANENT DICTIONARY MANUAL
UNDO_TBS01 UNDO LOCAL MANUAL
TMP01 TEMPORARY LOCAL MANUAL
TBS_16K PERMANENT LOCAL AUTO
BIG_TBS PERMANENT LOCAL AUTO
15 rows selected.
6、建立对象的存储信息：
03:35:07 SQL> create table test (id int) tablespace users;
Table created.
03:35:22 SQL> insert into test values (1);
1 row created.
03:35:31 SQL> insert into test values (2);
1 row created.
03:35:33 SQL> insert into test values (3);
1 row created.
03:35:34 SQL> commit;
Commit complete.
03:40:42 SQL> select SEGMENT_NAME,SEGMENT_TYPE ,TABLESPACE_NAME,bytes/1024/1024,BLOCKS,extents ,initial_extent/1024/1024 from user_segments
03:40:43 2 where segment_name='TEST';
SEGMENT_NAME SEGMENT_TYPE TABLESPACE_NAME BYTES/1024/1024 BLOCKS EXTENTS INITIAL_EXTENT/1024/1024
-------------------- ------------------ ------------------------------ --------------- ---------- ---------- ------------------------
TEST TABLE USERS 4 512 1 4
03:38:17 SQL> select TABLESPACE_NAME ,INITIAL_EXTENT/1024/1024 ,NEXT_EXTENT/1024/1024, EXTENT_MANAGEMENT from dba_tablespaces
03:38:24 2 where TABLESPACE_NAME='USERS';
TABLESPACE_NAME INITIAL_EXTENT/1024/1024 NEXT_EXTENT/1024/1024 EXTENT_MAN
------------------------------ ------------------------ --------------------- ----------
USERS 4 4 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
03:41:13 SQL> select segment_name,segment_type,TABLESPACE_NAME,EXTENT_ID,bytes/1024/1024,blocks from user_extents
03:42:04 2 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
03:43:53 SQL> select table_name, TABLESPACE_NAME ,PCT_FREE,INI_TRANS ,MAX_TRANS,NUM_ROWS,BLOCKS,EMPTY_BLOCKS from user_tables
03:44:41 2 where table_name='TEST';
TABLE_NAME TABLESPACE_NAME PCT_FREE INI_TRANS MAX_TRANS NUM_ROWS BLOCKS EMPTY_BLOCKS
------------------------------ ------------------------------ ---------- ---------- ---------- ---------- ---------- ------------
TEST USERS 10 1 255
03:45:17 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
03:45:26 SQL> select table_name, TABLESPACE_NAME ,PCT_FREE,INI_TRANS ,MAX_TRANS,NUM_ROWS,BLOCKS,EMPTY_BLOCKS from user_tables
03:45:28 2 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
03:45:29 SQL>
---------------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)
03:51:19 SQL> begin
03:51:33 2 for i in 4..100000 loop
03:51:43 3 insert into test values (i);
03:51:50 4 end loop;
03:51:52 5 end;
03:51:53 6 /
PL/SQL procedure successfully completed.
03:52:12 SQL> analyze table test compute statistics;
Table analyzed.
03:52:29 SQL> select table_name, TABLESPACE_NAME ,PCT_FREE,INI_TRANS ,MAX_TRANS,NUM_ROWS,BLOCKS,EMPTY_BLOCKS from user_tables
03:52:33 2 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
03:52:36 SQL>
建立autotrace ，跟踪sql语句
03:53:04 SQL> conn /as sysdba
Connected.
03:53:09 SQL> @?/rdbms/admin/utlxplan
Table created.
03:53:34 SQL> grant all on plan_table to public;
Grant succeeded.
03:53:43 SQL> @?/sqlplus/admin/plustrce
03:53:58 SQL>
03:53:58 SQL> drop role plustrace;
drop role plustrace
*
ERROR at line 1:
ORA-01919: role 'PLUSTRACE' does not exist
03:53:58 SQL> create role plustrace;
Role created.
03:53:58 SQL>
03:53:58 SQL> grant select on v_$sesstat to plustrace;
Grant succeeded.
03:53:58 SQL> grant select on v_$statname to plustrace;
Grant succeeded.
03:53:58 SQL> grant select on v_$mystat to plustrace;
Grant succeeded.
03:53:58 SQL> grant plustrace to dba with admin option;
Grant succeeded.
-------------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
03:53:58 SQL>
03:53:58 SQL> set echo off
03:53:58 SQL> grant plustrace to public;
Grant succeeded.
03:54:08 SQL>
------------对test 做全表扫描
03:54:53 SQL> set autotrace traceonly;
03:55:01 SQL> select * from test;
100000 rows selected.
Execution Plan
----------------------------------------------------------
Plan hash value: 1357081020
--------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------
| 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
03:55:08 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
03:56:19 SQL> col file_name for a50
03:56:23 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
14 rows selected.
03:56:24 SQL> alter database datafile 12 autoextend on next 10m maxsize 500m;
Database altered.
-----------undo tablespace自动扩展
03:57:07 SQL> delete from test;
100000 rows deleted.
04:00:02 SQL> set autotrace off
04:00:08 SQL> select table_name, TABLESPACE_NAME ,PCT_FREE,INI_TRANS ,MAX_TRANS,NUM_ROWS,BLOCKS,EMPTY_BLOCKS from user_tables
04:00:11 2 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
04:00:14 SQL>
----------delete 删除未释放占用的数据块
04:00:14 SQL> insert into test values (1);
1 row created.
04:00:58 SQL> insert into test values (2);
1 row created.
04:00:59 SQL> commit;
Commit complete.
04:01:01 SQL> set autotrace on;
04:01:09 SQL> select * from test;
ID
----------
1
2
Execution Plan
----------------------------------------------------------
Plan hash value: 1357081020
--------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 13 | 43 (3)| 00:00:01 |
| 1 | TABLE ACCESS FULL| TEST | 1 | 13 | 43 (3)| 00:00:01 |
--------------------------------------------------------------------------
Statistics
----------------------------------------------------------
1 recursive calls
0 db block gets
185 consistent gets
0 physical reads
0 redo size
451 bytes sent via SQL*Net to client
384 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使用也要访问所有已经使用过的块（扫描到HWM)
04:01:15 SQL> set autotrace off
04:02:32 SQL> truncate table test;
Table truncated.
04:02:35 SQL> analyze table test compute statistics;
Table analyzed.
04:02:44 SQL> select table_name, TABLESPACE_NAME ,PCT_FREE,INI_TRANS ,MAX_TRANS,NUM_ROWS,BLOCKS,EMPTY_BLOCKS from user_tables
04:02:49 2 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
04:02:52 SQL> 04:00:14 SQL> insert into test values (1);
SP2-0734: unknown command beginning "04:00:14 S..." - rest of line ignored.
04:03:01 SQL> insert into test values (1);
1 row created.
04:03:03 SQL> insert into test values (2);
1 row created.
04:03:05 SQL> commit;
Commit complete.
04:03:33 SQL> analyze table test compute statistics;
Table analyzed.
04:05:36 SQL> select table_name, TABLESPACE_NAME ,PCT_FREE,INI_TRANS ,MAX_TRANS,NUM_ROWS,BLOCKS,EMPTY_BLOCKS from user_tables
04:05:41 2 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
04:03:06 SQL> set autotrace on
04:03:10 SQL> select * from test;
ID
----------
1
2
Execution Plan
----------------------------------------------------------
Plan hash value: 1357081020
--------------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time |
--------------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 13 | 2 (0)| 00:00:01 |
| 1 | TABLE ACCESS FULL| TEST | 1 | 13 | 2 (0)| 00:00:01 |
--------------------------------------------------------------------------
Statistics
----------------------------------------------------------
1 recursive calls
0 db block gets
22 consistent gets
0 physical reads
0 redo size
451 bytes sent via SQL*Net to client
384 bytes received via SQL*Net from client
2 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
2 rows processed
04:03:33 SQL>
------------truncate 释放高水位线
04:08:55 SQL> create table t01 (id int)
04:08:59 2 pctfree 20 pctused 40 initrans 3
04:09:01 3 storage( initial 128k next 1m pctincrease 50);
Table created.
04:10:28 SQL> select table_name,TABLESPACE_NAME,PCT_FREE,PCT_USED ,INI_TRANS,INITIAL_EXTENT/1024,NEXT_EXTENT/1024/1024,PCT_INCREASE from user_tables
04:10:53 2 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
04:12:26 SQL> select owner, SEGMENT_NAME,TABLESPACE_NAME, BYTES from dba_segments
04:12:44 2 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.
