Oracle常用系统表及常用语句集合

1、常用的系统表

1.1 dba_

dba_users数据库用户信息 dba_segments 表段信息 dba_extents 数据区信息 dba_objects 数据库对象信息

dba_tablespaces 数据库表空间信息 dba_data_files 数据文件设置信息 dba_temp_files 临时数据文件信息 dba_rollback_segs 回滚段信息

dba_ts_quotas 用户表空间配额信息 dba_free_space 数据库空闲空间信息 dba_profiles 数据库用户资源限制信息 dba_sys_privs 用户的系统权限信息

dba_tab_privs 用户具有的对象权限信息 dba_col_privs 用户具有的列对象权限信息 dba_role_privs 用户具有的角色信息 dba_audit_trail 审计跟踪记录信息 dba_stmt_audit_opts 审计设置信息 dba_audit_object 对象审计结果信息 dba_audit_session 会话审计结果信息 dba_indexes 用户模式的索引信息

1.2user_

user_objects 用户对象信息

user_source 数据库用户的所有资源对象信息 user_segments 用户的表段信息 user_tables 用户的表对象信息 user_tab_columns 用户的表列信息 user_constraints 用户的对象约束信息 user_sys_privs 当前用户的系统权限信息 user_tab_privs 当前用户的对象权限信息 user_col_privs 当前用户的表列权限信息 user_role_privs 当前用户的角色权限信息 user_indexes 用户的索引信息

user_ind_columns 用户的索引对应的表列信息 user_cons_columns 用户的约束对应的表列信息 user_clusters 用户的所有簇信息

user_clu_columns 用户的簇所包含的内容信息 user_cluster_hash_expressions 散列簇的信息

1.3 v$（系统视图）

v$database 数据库信息 v$datafile 数据文件信息 v$controlfile 控制文件信息 v$logfile 重做日志信息 v$instance 数据库实例信息 v$log 日志组信息

v$loghist 日志历史信息 v$sga 数据库SGA信息

v$parameter 初始化参数信息 v$process 数据库服务器进程信息 v$bgprocess 数据库后台进程信息

v$controlfile_record_section 控制文件记载的各部分信息 v$thread 线程信息

v$datafile_header 数据文件头所记载的信息 v$archived_log 归档日志信息

v$archive_dest 归档日志的设置信息

v$logmnr_contents 归档日志分析的DML DDL结果信息 v$logmnr_dictionary 日志分析的字典文件信息 v$logmnr_logs 日志分析的日志列表信息 v$tablespace 表空间信息 v$tempfile 临时文件信息

v$filestat 数据文件的I/O统计信息 v$undostat Undo数据信息 v$rollname 在线回滚段信息 v$session 会话信息 v$transaction 事务信息 v$rollstat 回滚段统计信息 v$pwfile_users 特权用户信息

v$sqlarea 当前查询过的sql语句访问过的资源及相关的信息 v$sql 与v$sqlarea基本相同的相关信息 v$sysstat 数据库系统状态信息

1.4 all_

all_users 数据库所有用户的信息 all_objects 数据库所有的对象的信息

all_def_audit_opts 所有默认的审计设置信息 all_tables 所有的表对象信息

all_indexes 所有的数据库对象索引的信息

1.5 session_

session_roles 会话的角色信息 session_privs 会话的权限信息

1.6 index_

index_stats 索引的设置和存储信息

1.7 伪表

dual 系统伪列表信息

Dual 是 Oracle中的一个实际存在的表，任何用户均可读取，常用在没有目标表的Select中。 使用方法：

查看当前连接用户

SQL> select user from dual; USER-- SYSTEM

查看当前日期、时间

SQL> select sysdate from dual; SYSDATE--

18-3月 -01

SQL> select to_char(sysdate,'yyyy-mm-dd hh24:mi:ss') from dual; TO_CHAR(SYSDATE,'YY--- 2001-03-18 22:37:56

当作计算器用

SQL> select 1+2 from dual; 查看序列值

create sequence aaa increment by 1 start with 1; select aaa.nextval from dual; select aaa.currval from dual;

常用SQL查询：

1、查看表空间的名称及大小

select t.tablespace_name, round(sum(bytes/(1024*1024)),0) ts_size from dba_tablespaces t, dba_data_files d where t.tablespace_name = d.tablespace_name group by t.tablespace_name;

2、查看表空间物理文件的名称及大小

select tablespace_name, file_id, file_name, round(bytes/(1024*1024),0) total_space from dba_data_files

order by tablespace_name;

3、查看回滚段名称及大小

select segment_name, tablespace_name, r.status,

(initial_extent/1024) InitialExtent,(next_extent/1024) NextExtent,

max_extents, v.curext CurExtent

From dba_rollback_segs r, v$rollstat v Where r.segment_id = v.usn(+) order by segment_name;

4、查看控制文件

select name from v$controlfile;

5、查看日志文件

select member from v$logfile;

6、查看表空间的使用情况

select sum(bytes)/(1024*1024) as free_space,tablespace_name from dba_free_space

group by tablespace_name;

SELECT A.TABLESPACE_NAME,A.BYTES TOTAL,B.BYTES USED, C.BYTES FREE, (B.BYTES*100)/A.BYTES \FROM SYS.SM$TS_AVAIL A,SYS.SM$TS_USED B,SYS.SM$TS_FREE C WHERE A.TABLESPACE_NAME=B.TABLESPACE_NAME AND A.TABLESPACE_NAME=C.TABLESPACE_NAME;

7、查看数据库库对象

select owner, object_type, status, count(*) count# from all_objects group by owner, object_type, status;

8、查看数据库的版本

Select version FROM Product_component_version Where SUBSTR(PRODUCT,1,6)='Oracle';

9、查看数据库的创建日期和归档方式

Select Created, Log_Mode, Log_Mode From V$Database;

10、捕捉运行很久的SQL

column username format a12 column opname format a16 column progress format a8

select username,sid,opname,

round(sofar*100 / totalwork,0) || '%' as progress, time_remaining,sql_text from v$session_longops , v$sql where time_remaining <> 0 and sql_address = address

and sql_hash_value = hash_value /

11。查看数据表的参数信息

SELECT partition_name, high_value, high_value_length, tablespace_name,

pct_free, pct_used, ini_trans, max_trans, initial_extent,

next_extent, min_extent, max_extent, pct_increase, FREELISTS, freelist_groups, LOGGING, BUFFER_POOL, num_rows, blocks,

empty_blocks, avg_space, chain_cnt, avg_row_len, sample_size, last_analyzed

FROM dba_tab_partitions

--WHERE table_name = :tname AND table_owner = :towner ORDER BY partition_position

12.查看还没提交的事务

select * from v$locked_object; select * from v$transaction;

13。查找object为哪些进程所用

select p.spid,s.sid,s.serial# serial_num,s.username user_name,a.type object_type,s.osuser os_user_name,a.owner,a.object object_name,

decode(sign(48 - command),1,to_char(command), 'Action Code #' || to_char(command) ) action,p.program oracle_process,s.terminal terminal, s.program program,s.status session_status from v$session s, v$access a, v$process p

where s.paddr = p.addr and s.type = 'USER' and a.sid = s.sid and a.object='SUBSCRIBER_ATTR' order by s.username, s.osuser

14。回滚段查看 select rownum, sys.dba_rollback_segs.segment_name Name, v$rollstat.extents

Extents, v$rollstat.rssize Size_in_Bytes, v$rollstat.xacts XActs,

v$rollstat.gets Gets, v$rollstat.waits Waits, v$rollstat.writes Writes, sys.dba_rollback_segs.status status from v$rollstat, sys.dba_rollback_segs, v$rollname where v$rollname.name(+) =

sys.dba_rollback_segs.segment_name and

v$rollstat.usn (+) = v$rollname.usn order by rownum

15。耗资源的进程（top session）

select s.schemaname schema_name, decode(sign(48 - command), 1,

to_char(command), 'Action Code #' || to_char(command) ) action, status

session_status, s.osuser os_user_name, s.sid, p.spid , s.serial# serial_num,

nvl(s.username, '[Oracle process]') user_name, s.terminal terminal, s.program program, st.value criteria_value from v$sesstat st, v$session s , v$process p

where st.sid = s.sid and st.statistic# = to_number('38') and ('ALL' = 'ALL'

or s.status = 'ALL') and p.addr = s.paddr order by st.value desc, p.spid asc, s.username asc, s.osuser asc

16。查看锁（lock）情况

select /*+ RULE */ ls.osuser os_user_name, ls.username user_name, decode(ls.type, 'RW', 'Row wait enqueue lock', 'TM', 'DML enqueue lock', 'TX',

'Transaction enqueue lock', 'UL', 'User supplied lock') lock_type, o.object_name object, decode(ls.lmode, 1, null, 2, 'Row Share', 3, 'Row Exclusive', 4, 'Share', 5, 'Share Row Exclusive', 6, 'Exclusive', null)

lock_mode, o.owner, ls.sid, ls.serial# serial_num, ls.id1, ls.id2

from sys.dba_objects o, ( select s.osuser, s.username, l.type, l.lmode, s.sid, s.serial#, l.id1, l.id2 from v$session s,

v$lock l where s.sid = l.sid ) ls where o.object_id = ls.id1 and o.owner

<> 'SYS' order by o.owner, o.object_name

17。查看等待（wait）情况

SELECT v$waitstat.class, v$waitstat.count count, SUM(v$sysstat.value) sum_value

FROM v$waitstat, v$sysstat WHERE v$sysstat.name IN ('db block gets', 'consistent gets') group by v$waitstat.class, v$waitstat.count

18。查看sga情况

SELECT NAME, BYTES FROM SYS.V_$SGASTAT ORDER BY NAME ASC

19。查看catched object

SELECT owner, name, db_link, namespace,

type, sharable_mem, loads, executions,

locks, pins, kept FROM v$db_object_cache

20。查看V$SQLAREA

SELECT SQL_TEXT, SHARABLE_MEM, PERSISTENT_MEM, RUNTIME_MEM, SORTS, VERSION_COUNT, LOADED_VERSIONS, OPEN_VERSIONS, USERS_OPENING, EXECUTIONS,

USERS_EXECUTING, LOADS, FIRST_LOAD_TIME, INVALIDATIONS, PARSE_CALLS, DISK_READS,

BUFFER_GETS, ROWS_PROCESSED FROM V$SQLAREA；

21。查看object分类数量 select decode (o.type#,1,'INDEX' , 2,'TABLE' , 3 , 'CLUSTER' , 4, 'VIEW' , 5 ,

'SYNONYM' , 6 , 'SEQUENCE' , 'OTHER' ) object_type , count(*) quantity from

sys.obj$ o where o.type# > 1 group by decode (o.type#,1,'INDEX' , 2,'TABLE' , 3

, 'CLUSTER' , 4, 'VIEW' , 5 , 'SYNONYM' , 6 , 'SEQUENCE' , 'OTHER' ) union select

'COLUMN' , count(*) from sys.col$ union select 'DB LINK' , count(*) from

22。按用户查看object种类

select u.name schema, sum(decode(o.type#, 1, 1, NULL)) indexes, sum(decode(o.type#, 2, 1, NULL)) tables, sum(decode(o.type#, 3, 1, NULL))

clusters, sum(decode(o.type#, 4, 1, NULL)) views, sum(decode(o.type#, 5, 1,

NULL)) synonyms, sum(decode(o.type#, 6, 1, NULL)) sequences,

sum(decode(o.type#, 1, NULL, 2, NULL, 3, NULL, 4, NULL, 5, NULL, 6, NULL, 1))

others from sys.obj$ o, sys.user$ u where o.type# >= 1 and u.user# =

o.owner# and u.name <> 'PUBLIC' group by u.name order by sys.link$ union select 'CONSTRAINT' , count(*) from sys.con$

23。有关connection的相关信息 1）查看有哪些用户连接

select s.osuser os_user_name, decode(sign(48 - command), 1, to_char(command),

'Action Code #' || to_char(command) ) action, p.program oracle_process,

status session_status, s.terminal terminal, s.program program, s.username user_name, s.fixed_table_sequence activity_meter, '' query,

0 memory, 0 max_memory, 0 cpu_usage, s.sid, s.serial# serial_num

from v$session s, v$process p where s.paddr=p.addr and s.type = 'USER'

order by s.username, s.osuser

2）根据v.sid查看对应连接的资源占用等情况 select n.name, v.value, n.class,

n.statistic#

from v$statname n, v$sesstat v

where v.sid = 71 and

v.statistic# = n.statistic# order by n.class, n.statistic#

3）根据sid查看对应连接正在运行的sql select /*+ PUSH_SUBQ */ command_type, sql_text,

sharable_mem, persistent_mem, runtime_mem, sorts,

version_count, loaded_versions, open_versions, users_opening, executions,

users_executing, loads,

first_load_time, invalidations, parse_calls, disk_reads, buffer_gets, rows_processed, sysdate start_time, sysdate finish_time,

'>' || address sql_address,

'N' status from v$sqlarea

where address = (select sql_address from v$session where sid = 71)

24．查询表空间使用情况

select a.tablespace_name \表空间名称\

100-round((nvl(b.bytes_free,0)/a.bytes_alloc)*100,2) \占用率(%)\round(a.bytes_alloc/1024/1024,2) \容量(M)\

round(nvl(b.bytes_free,0)/1024/1024,2) \空闲(M)\

round((a.bytes_alloc-nvl(b.bytes_free,0))/1024/1024,2) \使用(M)\Largest \最大扩展段(M)\

to_char(sysdate,'yyyy-mm-dd hh24:mi:ss') \采样时间\from (select f.tablespace_name, sum(f.bytes) bytes_alloc,

sum(decode(f.autoextensible,'YES',f.maxbytes,'NO',f.bytes)) maxbytes

from dba_data_files f

group by tablespace_name) a, (select f.tablespace_name, sum(f.bytes) bytes_free from dba_free_space f

group by tablespace_name) b,

(select round(max(ff.length)*16/1024,2) Largest, ts.name tablespace_name

from sys.fet$ ff, sys.file$ tf,sys.ts$ ts

where ts.ts#=ff.ts# and ff.file#=tf.relfile# and ts.ts#=tf.ts# group by ts.name, tf.blocks) c

where a.tablespace_name = b.tablespace_name and a.tablespace_name = c.tablespace_name

25. 查询表空间的碎片程度

select tablespace_name,count(tablespace_name) from dba_free_space group by tablespace_name

having count(tablespace_name)>10;

alter tablespace name coalesce; alter table name deallocate unused;

create or replace view ts_blocks_v as

select tablespace_name,block_id,bytes,blocks,'free space' segment_name from dba_free_space union all select tablespace_name,block_id,bytes,blocks,segment_name from

dba_extents;

select * from ts_blocks_v;

select tablespace_name,sum(bytes),max(bytes),count(block_id) from dba_free_space

group by tablespace_name;

26。查询有哪些数据库实例在运行

select inst_name from v$active_instances;

===========================================================

######### 创建数据库----look $ORACLE_HOME/rdbms/admin/buildall.sql #############

create database db01 maxlogfiles 10 maxdatafiles 1024 maxinstances 2 logfile

GROUP 1 ('/u01/oradata/db01/log_01_db01.rdo') SIZE 15M, GROUP 2 ('/u01/oradata/db01/log_02_db01.rdo') SIZE 15M, GROUP 3 ('/u01/oradata/db01/log_03_db01.rdo') SIZE 15M, datafile 'u01/oradata/db01/system_01_db01.dbf') SIZE 100M, undo tablespace UNDO

datafile '/u01/oradata/db01/undo_01_db01.dbf' SIZE 40M default temporary tablespace TEMP

tempfile '/u01/oradata/db01/temp_01_db01.dbf' SIZE 20M extent management local uniform size 128k character set AL32UTE8

national character set AL16UTF16 set time_zone='America/New_York';

############### 数据字典 ##########

set wrap off

select * from v$dba_users;

grant select on table_name to user/rule;

select * from user_tables;

select * from all_tables;

select * from dba_tables;

revoke dba from user_name;

shutdown immediate

startup nomount

select * from v$instance;

select * from v$sga;

select * from v$tablespace;

alter session set nls_language=american;

alter database mount;

select * from v$database;

alter database open;

desc dictionary

select * from dict;

desc v$fixed_table;

select * from v$fixed_table;

set oracle_sid=foxconn

select * from dba_objects;

set serveroutput on

execute dbms_output.put_line('sfasd');

############# 控制文件 ###########

select * from v$database;

select * from v$tablespace;

select * from v$logfile;

select * from v$log;

select * from v$backup;

/*备份用户表空间*/

alter tablespace users begin backup;

select * from v$archived_log;

select * from v$controlfile;

alter system set control_files='$ORACLE_HOME/oradata/u01/ctrl01.ctl', '$ORACLE_HOME/oradata/u01/ctrl02.ctl' scope=spfile; cp $ORACLE_HOME/oradata/u01/ctrl01.ctl $ORACLE_HOME/oradata/u01/ctrl02.ctl

startup pfile='../initSID.ora'

select * from v$parameter where name like 'control%' ;

show parameter control;

select * from v$controlfile_record_section;

select * from v$tempfile;

/*备份控制文件*/

alter database backup controlfile to '../filepath/control.bak';

/*备份控制文件，并将二进制控制文件变为了asc 的文本文件*/ alter database backup controlfile to trace;

############### redo log ##############

archive log list;

alter system archive log start;--启动自动存档

alter system switch logfile;--强行进行一次日志switch

alter system checkpoint;--强制进行一次checkpoint

alter tablspace users begin backup;

alter tablespace offline;

/*checkpoint 同步频率参数FAST_START_MTTR_TARGET,同步频率越高，系统恢复所需时间越短*/ show parameter fast;

show parameter log_checkpoint;

/*加入一个日志组*/ alter database add logfile group 3 ('/$ORACLE_HOME/oracle/ora_log_file6.rdo' size 10M);

/*加入日志组的一个成员*/ alter database add logfile member '/$ORACLE_HOME/oracle/ora_log_file6.rdo' to group 3;

/*删除日志组:当前日志组不能删；活动的日志组不能删；非归档的日志组不能删*/

alter database drop logfile group 3;

/*删除日志组中的某个成员，但每个组的最后一个成员不能被删除*/ alter databse drop logfile member '$ORACLE_HOME/oracle/ora_log_file6.rdo';

/*清除在线日志*/

alter database clear logfile '$ORACLE_HOME/oracle/ora_log_file6.rdo';

alter database clear logfile group 3;

/*清除非归档日志*/

alter database clear unarchived logfile group 3;

/*重命名日志文件*/

alter database rename file '$ORACLE_HOME/oracle/ora_log_file6.rdo' to '$ORACLE_HOME/oracle/ora_log_file6a.rdo';

show parameter db_create;

alter system set db_create_online_log_dest_1='path_name';

select * from v$log;

select * from v$logfile;

/*数据库归档模式到非归档模式的互换,要启动到mount状态下才能改变;startup mount;然后再打开数据库.*/ alter database noarchivelog/archivelog;

achive log start;---启动自动归档

alter system archive all;－－手工归档所有日志文件

select * from v$archived_log;

show parameter log_archive;

###### 分析日志文件logmnr ##############

1) 在init.ora中set utl_file_dir 参数 2) 重新启动oracle 3) create 目录文件 desc dbms_logmnr_d; dbms_logmnr_d.build;

4) 加入日志文件 add/remove log file dhms_logmnr.add_logfile dbms_logmnr.removefile 5) start logmnr

dbms_logmnr.start_logmnr

6) 分析出来的内容查询 v$logmnr_content --sqlredo/sqlundo

实践：

desc dbms_logmnr_d;

/*对数据表做一些操作，为恢复操作做准备*/ update 表 set qty=10 where stor_id=6380;

delete 表 where stor_id=7066;

/***********************************/ utl_file_dir的路径 execute

dbms_logmnr_d.build('foxdict.ora','$ORACLE_HOME/oracle/admin/fox/cdump');

execute

dbms_logmnr.add_logfile('$ORACLE_HOME/oracle/ora_log_file6.log',dbms_logmnr.newfile);

execute

dbms_logmnr.start_logmnr(dictfilename=>'$ORACLE_HOME/oracle/admin/fox/cdump/foxdict.ora');

######### tablespace ##############

select * form v$tablespace;

select * from v$datafile;

/*表空间和数据文件的对应关系*/

select t1.name,t2.name from v$tablespace t1,v$datafile t2 where t1.ts#=t2.ts#;

alter tablespace users add datafile 'path' size 10M;

select * from dba_rollback_segs;

/*限制用户在某表空间的使用限额*/

alter user user_name quota 10m on tablespace_name;

create tablespace xxx [datafile 'path_name/datafile_name'] [size xxx] [extent management local/dictionary] [default storage(xxx)];

exmple: create tablespace userdata datafile '$ORACLE_HOME/oradata/userdata01.dbf' size 100M AUTOEXTEND ON NEXT 5M MAXSIZE 200M; create tablespace userdata datafile '$ORACLE_HOME/oradata/userdata01.dbf' size 100M extent management dictionary default storage(initial 100k next 100k pctincrease 10) offline; /*9i以后，oracle建议使用local管理，而不使用dictionary管理，因为local采用bitmap管理表空间 ，不会产生系统表空间的自愿争用;*/ create tablespace userdata datafile '$ORACLE_HOME/oradata/userdata01.dbf' size 100M extent management local uniform size 1m; create tablespace userdata datafile '$ORACLE_HOME/oradata/userdata01.dbf' size 100M extent management local autoallocate;

/*在创建表空间时，设置表空间内的段空间管理模式，这里用的是自动管理*/ create tablespace userdata datafile '$ORACLE_HOME/oradata/userdata01.dbf' size 100M extent management local uniform size 1m segment space management auto;

alter tablespace userdata mininum extent 10;

alter tablespace userdata default storage(initial 1m next 1m pctincrease 20);

/*undo tablespace(不能被用在字典管理模下) */ create undo tablespace undo1 datafile '$ORACLE_HOME/oradata/undo101.dbf' size 40M extent management local;

show parameter undo;

/*temporary tablespace*/ create temporary tablespace userdata tempfile '$ORACLE_HOME/oradata/undo101.dbf' size 10m extent management local;

/*设置数据库缺省的临时表空间*/

alter database default temporary tablespace tablespace_name;

/*系统/临时/在线的undo表空间不能被offline*/ alter tablespace tablespace_name offline/online;

alter tablespace tablespace_name read only;

/*重命名用户表空间*/ alter tablespace tablespace_name rename datafile '$ORACLE_HOME/oradata/undo101.dbf' to '$ORACLE_HOME/oradata/undo102.dbf';

/*重命名系统表空间 ,但在重命名前必须将数据库shutdown,并重启到mount状态*/

alter database rename file '$ORACLE_HOME/oradata/system01.dbf' to '$ORACLE_HOME/oradata/system02.dbf';

drop tablespace userdata including contents and datafiles;---drop tablespce

/*resize tablespace,autoextend datafile space*/

alter database datafile '$ORACLE_HOME/oradata/undo102.dbf' autoextend on next 10m maxsize 500M;

/*resize datafile*/

alter database datafile '$ORACLE_HOME/oradata/undo102.dbf' resize 50m;

/*给表空间扩展空间*/ alter tablespace userdata add datafile '$ORACLE_HOME/oradata/undo102.dbf' size 10m;

/*将表空间设置成OMF状态*/

alter system set db_create_file_dest='$ORACLE_HOME/oradata';

create tablespace userdata;---use OMF status to create tablespace;

drop tablespace userdata;---user OMF status to drop tablespace;

select * from dba_tablespace/v$tablespace/dba_data_files;

/*将表的某分区移动到另一个表空间*/

alter table table_name move partition partition_name tablespace tablespace_name;

###### ORACLE storage structure and relationships #########

/*手工分配表空间段的分区(extend)大小*/

alter table kong.test12 allocate extent(size 1m datafile '$ORACLE_HOME/oradata/undo102.dbf');

alter table kong.test12 deallocate unused; ---释放表中没有用到的分区

show parameter db;

alter system set db_8k_cache_size=10m; ---配置8k块的内存空间块参数

select * from dba_extents/dba_segments/data_tablespace;

select * from dba_free_space/dba_data_file/data_tablespace;

/*数据对象所占用的字节数*/

select sum(bytes) from dba_extents where onwer='kong' and segment_name ='table_name';

############ UNDO Data ################

show parameter undo;

alter tablespace users offline normal;

alter tablespace users offline immediate;

recover datafile '$ORACLE_HOME/oradata/undo102.dbf';

alter tablespace users online ;

select * from dba_rollback_segs;

alter system set undo_tablespace=undotbs1;

/*忽略回滚段的错误提示*/

alter system set undo_suppress_errors=true;

/*在自动管理模式下,不会真正建立rbs1;在手工管理模式则可以建立,且是私有回滚段*/

create rollback segment rbs1 tablespace undotbs;

desc dbms_flashback;

/*在提交了修改的数据后,9i提供了旧数据的回闪操作,将修改前的数据只读给用户看,但这部分数据不会又恢复在表中,而是旧数据的一个映射*/

execute dbms_flashback.enable_at_time('26-JAN-04:12:17:00 pm');

execute dbms_flashback.disable;

/*回滚段的统计信息*/

select end_time,begin_time,undoblks from v$undostat;

/*undo表空间的大小计算公式: UndoSpace=[UR * (UPS * DBS)] + (DBS * 24) UR :UNDO_RETENTION 保留的时间(秒) UPS :每秒的回滚数据块

DBS:系统EXTENT和FILE SIZE(也就是db_block_size)*/

select * from dba_rollback_segs/v$rollname/v$rollstat/v$undostat/v$session/v$transaction;

show parameter transactions;

show parameter rollback;

/*在手工管理模式下,建立公共的回滚段*/

create public rollback segment prbs1 tablespace undotbs;

alter rollback segment rbs1 online;----在手工管理模式

/*在手工管理模式中,initSID.ora中指定 undo_management=manual 、rollback_segment=('rbs1','rbs2',...)、

transactions=100 、transactions_per_rollback_segment=10 然后 shutdown immediate ,startup pfile=....\\???.ora */

########## Managing Tables ###########

/*char type maxlen=2000;varchar2 type maxlen=4000 bytes rowid 是18位的64进制字符串 (10个bytes 80 bits) rowid组成: object#(对象号)--32bits,6位 rfile#(相对文件号)--10bits,3位 block#(块号)--22bits,6位 row#(行号)--16bits,3位

64进制: A-Z,a-z,0-9,/,+ 共64个符号

dbms_rowid 包中的函数可以提供对rowid的解释*/

select

rowid,dbms_rowid.rowid_block_number(rowid),dbms_rowid.rowid_row_number(rowid) from table_name;

create table test2 (

id int,

lname varchar2(20) not null,

fname varchar2(20) constraint ck_1 check(fname like 'k%'), empdate date default sysdate) ) tablespace tablespace_name;

create global temporary table test2 on commit delete/preserve rows as select * from kong.authors;

create table user.table(...) tablespace tablespace_name storage(...) pctfree10 pctused 40; alter table user.tablename pctfree 20 pctused 50 storage(...);---changing table storage

/*手工分配分区,分配的数据文件必须是表所在表空间内的数据文件*/

alter table user.table_name allocate extent(size 500k datafile '...');

/*释放表中没有用到的空间*/

alter table table_name deallocate unused;

alter table table_name deallocate unused keep 8k;

/*将非分区表的表空间搬到新的表空间,在移动表空间后，原表中的索引对象将会不可用，必须重建*/

alter table user.table_name move tablespace new_tablespace_name;

create index index_name on user.table_name(column_name) tablespace users;

alter index index_name rebuild;

drop table table_name [CASCADE CONSTRAINTS];

alter table user.table_name drop column col_name [CASCADE CONSTRAINTS CHECKPOINT 1000];---drop column

/*给表中不用的列做标记*/

alter table user.table_name set unused column comments CASCADE CONSTRAINTS;

/*drop表中不用的做了标记列*/

alter table user.table_name drop unused columns checkpoint 1000;

/*当在drop col是出现异常，使用CONTINUE，防止重删前面的column*/ ALTER TABLE USER.TABLE_NAME DROP COLUMNS CONTINUE CHECKPOINT 1000;

select * from dba_tables/dba_objects;

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