Oracle DBA常用SQL汇总

#查找被锁的对象：
select p.spid,
       c.object_name,
       b.session_id,
       b.oracle_username,
       b.os_user_name
  from v$process p, v$session a, v$locked_object b, all_objects c
 where p.addr = a.paddr
   and a.process = b.process
   and c.object_id = b.object_id;

RAC:
并行度参数，如
parallel_max_servers=256
parallel_min_servers=16
parallel_threads_per_cpu=2
parallel_execution_message_size=16384
跨节点并行的参数
instance_groups=crm,erp,oltp
parallel_instance_group=crm

#在linux使用top根据进程id号找出正在跑的sql(sql的前1000个字符)

select /*+ ordered */
 sql_text
  from v$sqltext a
 where (a.hash_value, a.address) in
       (select decode(sql_hash_value, 0, prev_hash_value, sql_hash_value),
               decode(sql_hash_value, 0, prev_sql_addr, sql_address)
          from v$session b, v$process c
         where b.paddr = c.addr
           and c.spid = '&pid')
 order by piece asc;

select s.username, s.sid, s.program, s.machine, s.osuser
  from v$session s, v$process p
 where s.paddr = p.addr
   and p.spid = '&pid';

#根据指定的事件抓出sql
select sql_text
  from v$sqltext a, v$session b, v$session_wait c
 where a.ADDRESS = b.SQL_ADDRESS
   and b.sid = c.sid
   and c.event = 'db file scattered read'
 order by piece asc;

 select sql_text
  from v$sqltext a, v$session b, v$session_wait c
 where a.ADDRESS = b.SQL_ADDRESS
   and b.sid = c.sid
   and c.event = 'read by other session'
 order by piece asc;

#根据sid查出spid然后进到系统里面进行kill
select p.spid from v$session s,v$process p where s.PADDR=p.ADDR and s.sid=100;

#根据sid查出正在运行的sql(完整sql)
select sql_text
  from v$sqltext_with_newlines st, v$session se
 where st.address = se.sql_address
   and st.hash_value = se.sql_hash_value
   and se.sid = 458
 order by piece;

#通过等待事件查找其集中在哪些对象
1）
Select count(*), event
  from v$session_wait
 where event not in ('smon timer', 'pmon timer', 'rdbms ipc message',
        'SQL*Net message from client')
 group by event
 order by 1 desc;
2）
进一步分析，找出等待事件（buffer busy waits）的原因
Select count(*), p1, p2, p3
  from v$session_wait
 where event = 'buffer busy waits'
 group by p1, p2, p3;
 
在buffer busy waits等待事件中
P1 = file#
P2 = block#
P3 = id ( 此id对应为等待的原因)
按照p1,p2,p3 group是为了明确buffer busy waits的等待集中在哪些对象上。
Metalink对buffer busy waits等待事件的描述有如下一段话：
“If P3 shows that the "buffer busy wait" is waiting for a block read to complete then the blocking session is likely to be waiting on an IO wait (eg: "db file sequential read" or "db file scattered read" for the same file# and block#.”
通过以下SQL可以找到具体的object.
3)
Select owner, segment_name, segment_type
  from dba_extents
 where file_id = P1
   and P2 between block_id and block_id + blocks;


##########对分区表的操作#############
1.查询分区表(ODS_MAIL_BILL)的某个分区(MAIL_BILL_200703)中的数据
select * from ODS_MAIL_BILL partition(MAIL_BILL_200703);
2.truncate表(ODS_MAIL_BILL)的某个分区(MAIL_BILL_200703)中的所有数据
alter table ODS_MAIL_BILL truncate partition MAIL_BILL_200703;
3.delete表(ODS_MAIL_BILL)的某个分区(MAIL_BILL_200703)中的所有数据
delete ODS_MAIL_BILL partition (MAIL_BILL_200703);
#查询分区表的某一个分区
select count(*) from RDT_P_MAIL_TRACK partition (P20080220);

#查询分区信息：分区名称，分区键最大值，分区编号，分区所在表空间
select partition_name, high_value, partition_position, tablespace_name
  from user_tab_partitions
 where table_name = 'T_PUB_JNL_SAV'
 order by partition_position desc;
#查询分区信息：分区表，分区方式，分区默认表空间
select * from user_part_tables;
#查询分区信息：分区字段名与位置，分区类型（表or索引）
select * from user_part_key_columns where name='T_PUB_JNL_SAV';

#truncate分区表中的某一个分区
alter table RDT_P_MAIL_TRACK truncate partition P20080220;

#drop分区表中的某一个分区
alter table RDT_P_MAIL_TRACK drop partition P20080220;

#增加分区表
alter table BILL_MONTHFEE_ZERO add Partition p_200409　values less than (200409) tablespace ts_ziken;

#将一个分区分为两个分区
alter table bill_monthfee_zero split Partition p_200409 at (200409) into (Partition p_200409_1 tablespace ts_ziken,
Partition p_200409_2 tablespace ts_ziken_idx);

#合并分区
ALTER TABLE bill_monthfee_zero　MERGE PARTITIONS p_200408, p_200409 INTO PARTITION p_all;

#将分区改名
alter table bill_monthfee_zero rename Partition p_200408 to p_fee_200408;

#将分区改表空间
alter table bill_monthfee_zero move Partition p_200409 tablespace ts_ziken_01 nologging;

#EXPORT指定分区：
exp sales/sales_password tables=RDT_P_MAIL_TRACK:P20080220 file=sales1999_q1.dmp

#IMPORT指定分区：
imp sales/sales_password FILE =sales1999_q1.dmp tables=(RDT_P_MAIL_TRACK:P20080220) ignore=y

#新建表空间
CREATE TABLESPACE DATA_HIST
    DATAFILE 'E:\DATA\ORC1\data_hist01.dbf' SIZE 2000M [blocksize 32k]
    EXTENT MANAGEMENT LOCAL
    uniform size 1M  ------通常3种uniform size 128k(1G以下表)/1m(1G~20G的表)/8m or 16m(20G以上表)
    SEGMENT SPACE MANAGEMENT AUTO;

#为表空间新增数据文件
alter tablespace data add datafile 'E:\DATA\ORC1\DATA03.dbf' size 2000m;

#更改数据文件的位置(在start mount状态下)
alter database rename file '/opt/oracle/test.dbf' to '/opt/oracle/oradata/conner/test.dbf';

###不论是否在归档模式,都可以通过离线表空间实现数据文件的位置改变:
1.alter tablespace xxx offline;
2.!cp /opt/oracle/test.dbf /opt/oracle/oradata/conner/test.dbf
3.alter tablespace xxx rename datafile '/opt/oracle/test.dbf' to '/opt/oracle/oradata/conner/test.dbf';
4.alter tablespace xxx online;

##删除cluster table
DROP CLUSTER emp_dept INCLUDING TABLES CASCADE CONSTRAINTS;

#改变数据文件大小
alter database datafile '/opt/oracle/oradata/shtd/shtd01.dbf' resize 2000m;

#丢失一个数据文件但是存在其日志，没有备份怎么恢复
#对于丢失一个数据文件的情况，必须要求该数据文件不能是系统的数据文件，而且控制文件记录有该数据文件的信息，并且保证有该数据文件创建以来的所有日志，则可以不利用备份恢复，只需要重新根据控制文件创建该数据文件并恢复即可。

代码:
SQL>startup mount
SQL>Alter database create datafile 'db file name' as 'db file name' size … reuse;
SQL>recover datafile n;
or
SQL>recover datafile 'db file name';

#没有备份，丢失数据文件
#对于这样的情况，如果没有任何备份，可能要承担数据的丢失（除非通过dul或者类似工具去数据文件中抓取数据）的风险。如果该数据文件不是系统数据文件，可以强行删除再打开数据库。如，在mount状态下：

代码:--------------------------------------------------------------------------------
--ARCHIVELOG模式命令
SQL>Alter database datafile 'file name' offline;
--NOARCHIVELOG模式命令
SQL>Alter database datafile 'file name' offline drop;
---------------------------------------------------------------------------------

#最后open数据库即可。
#当然，如果有备份是可以防止数据丢失的，可以从备份进行数据文件的恢复，如

代码:--------------------------------------------------------------------------------
rman> restore datafile n;
rman> recover datafile n;
---------------------------------------------------------------------------------


#8i修改回滚段的大小
alter rollback segment rbs0 offline;
drop rollback segment rbs0;
create public rollback segment rbs0 tablespace rbs storage (initial 150m);
alter rollback segment rbs0 online;

#查看某user具有哪些权限
select * from dba_role_privs where grantee='USERNAME';
select * from dba_sys_privs where grantee='USERNAME';
select * from dba_tab_privs where grantee='USERNAME';

#建立用户test，密码为password，默认表空间为ddd
create user test identified by password default tablespace ddd quota unlimited on ddd;

#给用户test授予connect角色
grant connect to test;

#拿掉用户test的connect角色
revoke connect from test;

#删除用户test，连带其下的所有表，索引，视图等所有物件
drop user test cascade;

select
#查询表空间使用情况（包含临时表空间）
set lin 160
set pagesize 9999
col tablespace_name for a20
col ext_manag for a10
col size_mb for a20
col used_mb for a20
col used_per for a10
SELECT d.status status,
       d.tablespace_name tablespace_name,
       d.contents type,
       d.extent_management ext_manag,
       TO_CHAR(NVL(a.bytes / 1024 / 1024, 0), '99,999,990.900') size_mb,
       TO_CHAR(NVL(a.bytes - NVL(f.bytes, 0), 0) / 1024 / 1024,'99,999,990.900')  used_mb,
       TO_CHAR(NVL((a.bytes - NVL(f.bytes, 0)) / a.bytes * 100, 0),'990.00') used_per
  FROM sys.dba_tablespaces d,
       (select tablespace_name, sum(bytes) bytes
          from dba_data_files
         group by tablespace_name) a,
       (select tablespace_name, sum(bytes) bytes
          from dba_free_space
         group by tablespace_name) f
 WHERE d.tablespace_name = a.tablespace_name(+)
   AND d.tablespace_name = f.tablespace_name(+)
   AND NOT
        (d.extent_management like 'LOCAL' AND d.contents like 'TEMPORARY')
UNION ALL
SELECT d.status status,
       d.tablespace_name tablespace_name,
       d.contents type,
       d.extent_management ext_manag,
       TO_CHAR(NVL(a.bytes / 1024 / 1024, 0), '99,999,990.900') size_mb,
       TO_CHAR(NVL(t.bytes, 0) / 1024 / 1024, '99,999,990.900') used_mb,
       TO_CHAR(NVL(t.bytes / a.bytes * 100, 0), '990.00') used_per
  FROM sys.dba_tablespaces d,
       (select tablespace_name, sum(bytes) bytes
          from dba_temp_files
         group by tablespace_name) a,
       (select tablespace_name, sum(bytes_cached) bytes
          from v$temp_extent_pool
         group by tablespace_name) t
 WHERE d.tablespace_name = a.tablespace_name(+)
   AND d.tablespace_name = t.tablespace_name(+)
   AND d.extent_management like 'LOCAL'
   AND d.contents like 'TEMPORARY';

#查询表空间的总大小
SELECT tablespace_name, SUM(BYTES) / 1024 / 1024 sizemb
  FROM dba_data_files
 GROUP BY tablespace_name;


#查看表空间的使用率：
SELECT a.tablespace_name,
       to_char(NVL((a.BYTES - NVL(f.BYTES, 0)), 0) * 100 / a.bytes, '90.99') || '%' used_rate
  FROM (SELECT tablespace_name, SUM(BYTES) BYTES
          FROM dba_data_files
         GROUP BY tablespace_name) a,
       (SELECT tablespace_name, SUM(BYTES) BYTES
          FROM dba_free_space
         GROUP BY tablespace_name) f
 WHERE a.tablespace_name = f.tablespace_name(+)
union all
select t.tablespace_name,
       to_char(t.user_bytes * 100 / t.bytes, '90.99') || '%' used_rate
  from (select tablespace_name, sum(user_bytes) user_bytes, sum(bytes) bytes
          from dba_temp_files
         group by tablespace_name) t


#查询用户username下的所有table的大小
SELECT owner, segment_name, segment_type, BYTES / 1024 / 1024 sizemb
  FROM dba_segments
 WHERE owner = 'USERNAME'
   AND segment_type = 'TABLE';

#Top SQL
SELECT username, sql_text, sofar, totalwork
FROM v$sql, v$session_longops
WHERE sql_address=address
    AND sql_hash_value=hash_value
ORDER BY address, hash_value, child_number;

select *
  from (select sql_text,
               disk_reads / greatest(executions, 1) D,
               disk_reads,
               buffer_gets,
               module,
               executions
          from v$sql
         order by D desc)
 where rownum <= 10;

select *
  from (select sql_text,
               buffer_gets / greatest(executions, 1) B,
               disk_reads,
               buffer_gets,
               module,
               executions
          from v$sql
         order by B desc)
 where rownum <= 10;

#SQL Trace(SQL跟踪)
select sid,serial#,username from v$session;
#假如查出来某用户的sid是7，serial#是284
exec dbms_system.set_sql_trace_in_session(7,284,true)
#开始跟踪了。。。
#等候一段时间，继续查询此sid,serial#,username是否还存在
#然后结束跟踪
exec dbms_system.set_sql_trace_in_session(7,284,true)
#格式化trace文件
tkprof sungnie_ora_15937.trc tracefile
#查看格式化以后的文件
vi tracefile.prf


###logminer---9i,以在PL/SQL Developer运行为例

begin
 DBMS_LOGMNR_D.BUILD(OPTIONS => DBMS_LOGMNR_D.STORE_IN_REDO_LOGS);
end;

begin
  dbms_logmnr.add_logfile(logfilename => '/opt/oracle/oradata/shzz/archive/1_68.dbf',
                          options     => dbms_logmnr.new);
end;

begin
  dbms_logmnr.add_logfile(logfilename => '/opt/oracle/oradata/shzz/archive/1_69.dbf',
                          options     => dbms_logmnr.addfile);
end;

............

begin
  dbms_logmnr.start_logmnr(options => dbms_logmnr.dict_from_redo_logs +
                                      dbms_logmnr.committed_data_only);
end;

select * from v$logmnr_contents;

begin
  dbms_logmnr.end_logmnr;
end;

###logminer---8i,以在PL/SQL Developer运行为例

#For example, to set UTL_FILE_DIR to use /opt/oracle/coohoo as the directory where the dictionary file is placed,
#enter the following in the init.ora file:

UTL_FILE_DIR = /opt/oracle/coohoo

begin
  dbms_logmnr_d.build('diction.ora', '/opt/oracle/coohoo');
end;

begin
  dbms_logmnr.add_logfile(logfilename => '/opt/oracle/admin/shzz/arch/arch_1_365.arc',
                          options     => dbms_logmnr.new);
end;

begin
  dbms_logmnr.add_logfile(logfilename => '/opt/oracle/admin/shzz/arch/arch_1_366.arc',
                          options     => dbms_logmnr.addfile);
end;

............

begin
  dbms_logmnr.start_logmnr(starttime    => to_date('2006-4-5 17:55:02',
                                                   'yyyy-mm-dd hh24:mi:ss'),
                           endtime      => to_date('2006-4-5 17:55:05',
                                                   'yyyy-mm-dd hh24:mi:ss'),
                           dictfilename => '/opt/oracle/coohoo/diction.ora');
end;

select * from v$logmnr_contents


####查找/tmp目录及其所有子目录中内容包含有test字符串的文件名####
#!/usr/bin/ksh
for FILE in `find /tmp -name "*"`
do
if
test "`cat $FILE|grep -c test`" -gt "0"
then
echo $FILE
fi
done

##online log的各项操作
alter database drop logfile member '/home5/yzstb/yz_redolog5b'

alter database add logfile member '/oracle/yz/u01/oradata/yz_redolog4b' to group 4

alter database add logfile group 6 '/oracle/yz/u01/oradata/yz_redolog6a' size 100m

alter database drop logfile group 1

#缩小数据文件
ALTER DATABASE DATAFILE '/opt/oracle/oradata/shtd/shtd01.dbf' RESIZE 1000M;


#创建JOB
variable jobno number;
begin
  dbms_job.submit(job=>:jobno,
                                what=> 'p_atm_init;',
                                next_date=>to_date('08-06-2011 10:59:00','dd-mm-yyyy hh24:mi:ss'),
                                interval=>'trunc(sysdate)+1+1/24',
                        instance=>2);
  commit;
end;
/
print jobno

#假如what后面内容里有引号要注意使用两个单引号，如：
variable jobno number;
begin
  dbms_job.submit(job=>:jobno,
                                what=> 'PKG_ATM_CHECK.p_check_qukuan(to_char(sysdate-7,''yyyymmdd''),to_char(sysdate-1,''yyyymmdd''));',
                                next_date=>to_date('08-06-2011 20:00:00','dd-mm-yyyy hh24:mi:ss'),
                                interval=>'trunc(sysdate)+1+8/24',
                        instance=>2);
  commit;
end;
/
print jobno


#submit函数参数：

job，作业的作业号，是个输出参数，所以调用submit函数时，这个参数要指定一个已存在的变量。

what，作业要执行的代码，一般是存储过程。

next_date，第一次运行job的时间，不指定则为当前时间

interval，作业执行的间隔时间，这个参数默认值是null，也就是what指定的代码只在next_date这一时间执行一次。

no_parse，默认值是false，当参数值是false，提交作业时就对what指定的代码进行语法分析；当参数值是true，第一次运行what指定代码时才进行语法分析。

instance，指明运行作业的数据库实例。

force，如果是true,instance可以是任何正数；如果是false，instance指定的实例必须正在运行。

#停止一个JOB
exec dbms_job.broken(1,true);
commit;

#启动作业
exec dbms_job.broken(1,false);
commit;

#删除job
exec dbms_job.remove(:job);
commit;

#立即执行job
exec dbms_job.run(:jobno);
commit;

#修改作业
execute dbms_job.change(186,null,null,'sysdate+3');
execute dbms_job.change(186,'scott.test(update)');
##或者这样写，指定在每天的某一固定时间（9点半）执行：
begin
  sys.dbms_job.change(job       => 25,
                      what      => 'P_UpdateXbdGazInfo;',
                      next_date => to_date('2009-06-23 09:30:00',
                                           'yyyy-mm-dd hh24:mi:ss'),
                      interval  => 'trunc(sysdate+1, ''hh24'') + 1/48');
  commit;
end;
/

#RAC中指定编号184的JOB在节点2上运行
exec dbms_job.instance(184,2);
commit;

####数据字典
DBA_JOBS
＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝
字段（列）          类型                 描述
JOB                NUMBER          任务的唯一标示号
LOG_USER           VARCHAR2(30)    提交任务的用户
PRIV_USER          VARCHAR2(30)    赋予任务权限的用户
SCHEMA_USER        VARCHAR2(30)    对任务作语法分析的用户模式
LAST_DATE          DATE            最后一次成功运行任务的时间
LAST_SEC           VARCHAR2(8)     如HH24:MM:SS格式的last_date日期的小时，分钟和秒
THIS_DATE     DATE            正在运行任务的开始时间，如果没有运行任务则为null
THIS_SEC     VARCHAR2(8)     如HH24:MM:SS格式的this_date日期的小时，分钟和秒
NEXT_DATE          DATE            下一次定时运行任务的时间
NEXT_SEC           VARCHAR2(8)     如HH24:MM:SS格式的next_date日期的小时，分钟和秒
TOTAL_TIME         NUMBER          该任务运行所需要的总时间，单位为秒
BROKEN             VARCHAR2(1)     标志参数，Y标示任务中断，以后不会运行
INTERVAL           VARCHAR2(200)   用于计算下一运行时间的表达式
FAILURES    NUMBER     任务运行连续没有成功的次数
WHAT               VARCHAR2(2000)  执行任务的PL/SQL块
CURRENT_SESSION_LABEL RAW          MLSLABEL 该任务的信任Oracle会话符
CLEARANCE_HI      RAW MLSLABEL     该任务可信任的Oracle最大间隙
CLEARANCE_LO      RAW              MLSLABEL 该任务可信任的Oracle最小间隙
NLS_ENV           VARCHAR2(2000)   任务运行的NLS会话设置
MISC_ENV          RAW(32)          任务运行的其他一些会话参数


描述                    INTERVAL参数值
每天午夜12点            'TRUNC(SYSDATE + 1)'
每天早上8点30分         'TRUNC(SYSDATE + 1) + （8*60+30）/(24*60)'
每星期二中午12点         'NEXT_DAY(TRUNC(SYSDATE ), ''TUESDAY'' ) + 12/24'
每个月第一天的午夜12点    'TRUNC(LAST_DAY(SYSDATE ) + 1)'
每个季度最后一天的晚上11点 'TRUNC(ADD_MONTHS(SYSDATE + 2/24, 3 ), 'Q' ) -1/24'
每星期六和日早上6点10分    'TRUNC(LEAST(NEXT_DAY(SYSDATE, ''SATURDAY"), NEXT_DAY(SYSDATE, "SUNDAY"))) + （6×60+10）/（24×60）'


############Linux&Unix下测试Disk读写速度：


#Write Performance: 产生一个4G file 并用 time 算出时间

/usr/bin/time dd if=/dev/zero of=./testfile bs=16384 count=250000

##产生2G的file
/usr/bin/time dd if=/dev/zero of=./testfile bs=16384 count=128000


#Read Performance: 用刚刚产生的4G file 读档 算出时间

/usr/bin/time dd if=./testfile of=/dev/null bs=16384

####重建控制文件的脚本：
####注意：'yz',character,logfile和datafile应与实际db相符

create controlfile reuse database 'yz' resetlogs noarchivelog
maxlogfiles 64
maxlogmembers 2
maxdatafiles 254
maxinstances 32
maxloghistory 113
logfile
group 1 '/oracle/yz/u01/oradata/yz_redolog1a' size 20972032,
group 2 '/oracle/yz/u01/oradata/yz_redolog2a' size 20972032,
group 3 '/oracle/yz/u01/oradata/yz_redolog3a' size 20972032,
group 4 '/oracle/yz/u01/oradata/yz_redolog4a' size 20972032,
group 5 '/oracle/yz/u01/oradata/yz_redolog5a' size 20972032
datafile
'/oracle/yz/u01/oradata/yz_system',
'/oracle/yz/u01/oradata/yz_tool',
'/oracle/yz/u01/oradata/yz_rbs1',
'/oracle/yz/u01/oradata/yz_temp1',
'/oracle/yz/u01/oradata/yz_basic',
'/oracle/yz/u01/oradata/yz_basic_inx',
'/oracle/yz/u01/oradata/yz_flow1',
'/oracle/yz/u01/oradata/yz_flow1_inx',
'/oracle/yz/u01/oradata/yz_flow2',
'/oracle/yz/u01/oradata/yz_flow2_inx',
'/oracle/yz/u01/oradata/yz_rbs2',
'/oracle/yz/u01/oradata/yz_rbs3',
'/oracle/yz/u01/oradata/yz_flow2_inx01',
'/oracle/yz/u01/oradata/yz_flow2_02',
'/oracle/yz/u01/oradata/yz_flow2_03',
'/oracle/yz/u01/oradata/yz_flow2_inx02'
CHARACTER SET ZHS16CGB231280;   --------->这一句有时候不需要


###to_char妙用
#今天是今年的第几天？
SELECT TO_CHAR(SYSDATE,'DDD') From Dual;
#今天是今年的第几周？
SELECT TO_CHAR(SYSDATE,'IW') From Dual;
#今天星期几？
select to_char(sysdate,'day') from dual;
#本月的天数？
SELECT to_char(last_day(SYSDATE),'dd') days FROM dual
#今年的天数？
select add_months(trunc(sysdate,'year'), 12) - trunc(sysdate,'year') from dual
#下个星期一的日期？
SELECT Next_day(SYSDATE,'monday') FROM dual

###在获取之前可以设置日期语言，如
ALTER SESSION SET NLS_DATE_LANGUAGE='AMERICAN';


##快速杀掉数据库进程
SQL> select sid,serial#,username from v$session where sid=154;

       SID    SERIAL# USERNAME
　　---------- ---------- ------------------------------
       154      56090 SCOTT

 

        再次在数据库中kill该session,并指定immediate选项:
　　SQL> alter system kill session ’154,56090’ immediate;

　　System altered.

##删除重复数据的一种高效的方法

##表demo是重复拷贝自dba_objects，有88万左右，不重复的是27323，没有索引
#方法一：delete from demo a where a.rowid <> (select max(rowid) from demo b where
                                                                      b.object_id=a.object_id);
            耗时：几个小时以上
#方法二： delete from demo where rowid in
              (select rid from
                          (select rowid rid,row_number() over(partition by object_id,object_name order by rowid) rn
                             from demo)
               where rn <> 1 );
   耗时：30秒   (这里的object_id,object_name表示有2个字段重复)
#方法三： create table demo2 as
              select object_id,owner... from
                       (select demo.*,row_number() over(partition by object_id order by rowid) rn from demo)
                         where rn = 1;
              truncate table demo; insert into demo select * from demo2; drop table demo2;
#共耗时： 10秒，适合大数据量的情况，产生更少回滚量；

#######调整SCN有两种常用方法:

1.通过immediate trace name方式(在数据库Open状态下)

alter session set events 'IMMEDIATE trace name ADJUST_SCN level x';

2.通过10015事件(在数据库无法打开，mount状态下)

alter session set events '10015 trace name adjust_scn level x';

注:level 1为增进SCN 10亿 (1 billion) (1024*1024*1024),通常Level 1已经足够。也可以根据实际情况适当调整。
#######

##对standby DB的操作###
recover standby database;
alter database mount standby database;
alter database recover managed standby database disconnect;
alter database recover managed standby database cancel;
alter database active physical standby database skip standby logfile;

####对RAC DB的操作
#9i RAC已经建好了，现在archive log的路径都是/arch1/racdb，另外还有一个共享的ocfs文件格式的/arch2，我想让2#个节点的archive log分别使用路径/arch1/racdb,/arch2/racdb。当我在instance1上使用alter system set #log_archive_dest_1="LOCATION=/arch1/racdb";时，发现两个instance的参数都改变了。
#怎样让两个instance的归档路径不同？（两个节点都已mount上了/arch1,/arch2）
alter system set log_archive_dest_1="LOCATION=/arch1/racdb" sid='rac1';




##############online redo log损坏#####
alter database clear logfile group n;
alter database clear unarchived logfile group n;


#########同时对用户mes1,mes4下的所有表、索引进行分析
begin
 dbms_stats.gather_schema_stats(ownname=> 'MES1' , cascade=> TRUE);
 dbms_stats.gather_schema_stats(ownname=> 'MES4' , cascade=> TRUE);
end;
/

#########对指定的表进行分析，包括索引，取样20%，并行度为4
exec dbms_stats.gather_table_stats(ownname=>'ABUSER',tabname=>'PUB_JNL_SAV',estimate_percent=>20,degree=>4,cascade=>true);
exec dbms_stats.gather_table_stats(ownname=>'ABUSER',tabname=>'TCS_INDPTY_AGMT_RELA_H',estimate_percent=>20,degree=>4,cascade=>true);


#########从rman的备份集中恢复出archivelog
run{
allocate channel t1 type 'SBT_TAPE';
restore archivelog from logseq=xxx until logseq=xxx thread 1;
release channel t1;
}


###############当undo表空间不能offline时,使用如下SQL找出在使用undo表空间的session
SELECT d.sid, d.serial#
  FROM v$rollstat a, v$rollname b, v$transaction c, v$session d
 WHERE a.USN = b.usn
   AND a.STATUS <> 'ONLINE'
   AND c.XIDUSN = a.USN
   AND c.ADDR = d.TADDR;


#############测量Buffer cache的命中率：
select 1 - ((physical.value - direct.value - lobs.value) / logical.value) "Buffer Cache Hit Ratio"
  from V$SYSSTAT physical,
       V$SYSSTAT direct,
       V$SYSSTAT lobs,
       V$SYSSTAT logical
 where physical.name = 'physical reads'
   and direct.name = 'physical reads direct'
   and lobs.name = 'physical reads direct (lob)'
   And logical.name = 'session logical reads';


############查看linux系统下磁盘的block大小，默认一般是4096
dumpe2fs -h /dev/sda5 |grep -F "Block size"


################standby db不限次数切换步骤
check 2 db:
select max(sequence#) from v$log_history;

PRIMARY:
select switchover_status from v$database;
if display:SESSIONS ACTIVE
alter database commit to switchover to physical standby with session shutdown;
if display:TO STANDBY
alter database commit to switchover to physical standby;

shutdown immediate;
startup nomount;
alter database mount standby database;
select database_role from v$database;
display: PHYSICAL STANDBY
alter database recover managed standby database disconnect from session;

STANDBY:
select switchover_status from v$database;
display: SESSIONS ACTIVE
alter database commit to switchover to primary with session shutdown;
shutdown immediate;
startup
select database_role from v$database;
if display: PRIMARY  then successful!!

Now change ip and listener.ora and tnsnames.ora and so on...
################standby db不限次数切换步骤


################表分析
begin
  dbms_stats.gather_schema_stats(ownname          => 'AIRPORT',
                                 options          => 'GATHER',
                                 estimate_percent => 20,
                                 method_opt       => 'for table for all indexes',
                                 degree           => 4,
                                 cascade          => true);
end;
/
begin
    DBMS_STATS.GATHER_TABLE_STATS(ownname=>'COOH',
                                  tabname=>'TEST_HISTO',
                                  estimate_percent=>30,
                                  method_opt=>'for columns object_id size 18',
                                  cascade=>true,
                                  degree=>4);
end;
/
begin
  DBMS_STATS.GATHER_TABLE_STATS(ownname          => 'AIRPORT',
                                tabname          => 'tmailflow',
                                estimate_percent => 20,
                                method_opt       => 'for all indexes',
                                cascade          => true,
                                degree           => 4);
end;
/
begin
  dbms_stats.delete_table_stats(ownname => 'AIRPORT', tabname => 'tmailflow');
end;
/
begin
  dbms_stats.delete_index_stats(ownname => 'AIRPORT',
                                indname => 'I_TMAILFLOW_SERIAL_ID');
end;
/
begin
  DBMS_STATS.GATHER_INDEX_STATS(ownname          => 'AIRPORT',
                                indname          => 'PK_TMAILFLOW',
                                estimate_percent => 30,
                                degree           => 4);
end;
/
begin
  DBMS_STATS.SET_INDEX_STATS(ownname => 'AIRPORT',
                             indname => 'PK_TMAILFLOW',
                             clstfct => 164597);
end;
/
begin
  dbms_stats.delete_column_stats(ownname => 'AIRPORT',
                                 TABNAME => 'tmailflow',
                                 COLNAME => 'mailid');
end;
/

#############################备注###########################################
为帮助进行明智的柱状图生成，Oracle 使用 dbms_stats 的 method_opt 参数;
在 method_opt 子句中还有重要的新选项，即 skewonly、repeat 和 auto;
DBMS_STATS默认不对索引进行分析，因为默认cascade是False，需要手工指定为True;
不能收集CHAINED ROWS,不能收集CLUSTER TABLE的信息，这两个仍旧需要使用Analyze语句;
使用estimate_percent => dbms_stats.auto_sample_size,可能会出现ORA-01555,
换成estimate_percent => 5能避免这一错误。
#############################备注############################################

#db link的建立方法：
-- Create database link use SID
create database link TWOLAN
  connect to JK_BFJ identified by POST
  using '(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=10.194.128.75)(PORT=1521)))(CONNECT_DATA=(SID=ora7)(SERVER=DEDICATED)))';
 
-- Create database link use SERVICE_NAME
create database link TIAOMA
  connect to TMHUSER identified by TMHTDXT
  using '(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=10.194.128.28)(PORT=1521)))(CONNECT_DATA=(SERVICE_NAME=orc1)))';

#parallel并行操作语句
create table c_district_backup parallel (degree 4) as select * from c_district;

insert /*+ parallel(xxxx,4) */ into xxxx select /*+ parallel(a) */ * from xxx a;   --此语句中2个hint，但只有into前面的hint生效

update /*+ PARALLEL (costs,4) */ costs set ......;

insert /*+ APPEND PARALLEL (COST_SUMMARY,4) */
into COST_SUMMARY
  (Prod_Id, Time_Id, Cost)
  select /*+ PARALLEL (COSTS, 6) */
   Prod_Id, Time_Id, SUM(Unit_Cost) Cost
    from COSTS
   group by Prod_Id, Time_Id;


#对于查询结果进行分页显示，加入指定显示从第2行到第3行：
SELECT *
  FROM (SELECT A.*, ROWNUM RN FROM (SELECT * FROM test) A WHERE ROWNUM <= 3)
 WHERE RN >= 2;

#如果获得当前的SCN
--oracle 10g:
select current_scn from v$database;
--oracle 9i
select dbms_flashback.get_system_change_number from dual;
--oracle 9i之前
select max(ktuxescnw*power(2,32)+ktuxescnb) from x$ktuxe;