数据库维护工作指南

数据库维护工作指南

1、创建新表流程

1.1 建表语句

CREATE TABLE tb_image

(

image_id NUMBER(16) NOT NULL,

suffix VARCHAR2(4) NOT NULL,

scenario CHAR(1) DEFAULT 0 NOT NULL,

creater NUMBER(16) NOT NULL,

create_time DATE NOT NULL,

CONSTRAINT pk_image

PRIMARY KEY (image_id) USING INDEX TABLESPACE CATIDX,

CONSTRAINT fk_image_creater

FOREIGN KEY (creater) REFERENCES tb_user(user_id)

) TABLESPACE CAT;

1) 如果字段名为关键字，则加双引号，例如："option"

2) 如果创建Unique，在外键声明下加上如下语句：CONSTRAINT UC_tb_visitor UNIQUE (mail) USING INDEX TABLESPACE ADMIDX

3) PK，FK，Unique命名请保持统一

1.2 创建sequence - 假如新表不需要sequence的话，则跳过

CREATE SEQUENCE seq_user MINVALUE 1000000000100001 MAXVALUE 9999999999999999 START WITH 1000000000100001 INCREMENT BY 1 NOCACHE;

1.3 授权

1）给table创建同义词

CREATE PUBLIC SYNONYM tb_acc_account FOR tb_acc_account;

2）给sequence创建同义词

CREATE PUBLIC SYNONYM seq_acc_journal FOR seq_acc_journal;

3）给table授权（根据相应的需求授予SELECT, INSERT, DELETE, UPDATE权限）

GRANT SELECT, INSERT, DELETE, UPDATE ON tb_activation_link TO om_app_role;

4）给sequence授权

GRANT SELECT ON seq_acc_journal TO om_app_role;

2、修改表结构

2.1 重命名表字段

ALTER TABLE tb_user RENAME COLUMN test_field TO test_field2;

2.2 增加新的字段

ALTER TABLE tb_user ADD test_field NUMBER(16) DEFAULT 0 NOT NULL;

2.3 删除字段

ALTER TABLE tb_user DROP COLUMN test_field;

2.4 更改字段

ALTER TABLE tb_user MODIFY test_field VARCHAR2(16) DEFAULT '0' NULL;

2.5 特殊情况

1) 例如修改字段类型VARCHAR2(2000)到CLOB,不能直接使用MODIFY，这时按以下流程操作：

ALTER TABLE tb_user ADD test_field2 CLOB DEFAULT 'NA' NOT NULL;

UPDATE tb_user SET test_field2=test_field;

COMMIT;

ALTER TABLE tb_user DROP COLUMN test_field;

ALTER TABLE tb_user RENAME COLUMN test_field2 TO test_field;

2.6 增加主键，外键，UNIQUE等

1）ALTER TABLE tb_acc_journal ADD CONSTRAINT PK_tb_user PRIMARY KEY (user_id) USING INDEX TABLESPACE DEALIDX；

2）ALTER TABLE tb_acc_journal ADD CONSTRAINT FK_tb_acc_journal_account FOREIGN KEY (account_id) REFERENCES tb_acc_account (acc_account_id)；

3）ALTER TABLE tb_item_category ADD CONSTRAINT UK_item_category_level_name UNIQUE(parent_cat_id,cat_name) USING INDEX TABLESPACE ADMIDX;

2.7 删除主键，外键，UNIQUE

1）ALTER TABLE tb_acc_journal DROP CONSTRAINT PK_tb_user；

2）ALTER TABLE tb_acc_journal DROP CONSTRAINT FK_tb_acc_journal_account；

3）ALTER TABLE tb_item_category DROP CONSTRAINT UK_item_category_level_name;

3、删除表

DROP TABLE tb_user CASCADE CONSTRAINTS;

4、Procedure和Job

1） 创建

CREATE OR REPLACE PROCEDURE bt_deal_promotion_visitor AS

BEGIN

update tb_visitor tv set tv.receive_mail_setting=bitor(tv.receive_mail_setting,1) where tv.mail in (select t.mail as email from tb_visitor t where t.status=1 and t.subscribe_sts!=9 and bitand(t.receive_mail_setting,1)=0

minus

select distinct substr(REGEXP_SUBSTR(t.referrer,'mail=[^&]+'),6) from tb_http_access_log t where t.url = '/unsubscribe/save' and t.referrer like '%/unsubscribe%' and (t.query_string is null or t.query_string like '%mailType=1%') and NOT REGEXP_LIKE(user_agent,
'(bot|scan|slurp|spider|craw)', 'i') and (ip <> '211.144.118.170' and ip <> '202.74.178.140' and ip <> '202.74.178.141'));

COMMIT;

END bt_deal_promotion_visitor;

/

var job NUMBER

begin

dbms_job.submit(:job,

'bt_deal_promotion_visitor;',

next_day(trunc(sysdate)+22/24,'SATURDAY'),

'trunc(sysdate+30)');

commit;

end;

/

2）查看

SQL> column log_user format a20

SQL> column WHAT format a50

SQL> column INTERVAL format a40

SQL> select job,log_user,what,next_date,next_sec,interval from user_jobs;

JOB LOG_USER WHAT NEXT_DATE NEXT_SEC INTERVAL

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

103 OM_SUPERVISOR bt_deal_promotion_visitor; 10/JUL/10 22:00:00 trunc(sysdate+30)

3）删除

begin

dbms_job.remove(103);

commit;

end;

/

drop procedure bt_deal_promotion_visitor;

4）暂停Job

begin

sys.dbms_job.broken(job => 103,

broken => true);

commit;

end;

/

5. Table Space

1） 改变表的表空间

alter table tablename move tablespace tabelspacename;

2）查看表空间的物理位置及具体参数

select * from dba_data_files where TABLESPACE_NAME='DEAL';

3）查看所有表空间的参数

select * from dba_tablespaces;

4) 查看表空间的空闲空间大小

select a.tablespace_name,b.file_name,sum(a.bytes) freespace,count(*) extcnt,b.bytes,max(a.bytes) largest,min(a.bytes) smallest

from dba_free_space a,dba_data_files b where a.tablespace_name=b.tablespace_name and a.file_id=b.file_id group by a.tablespace_name,b.file_name,b.bytes;

5) ORACLE中表、索引的表空间的批量更改方法

a. 查询当前用户下的所有表

select 'alter table '|| table_name ||' move tablespace
tablespacename;' from user_all_tables;

b. 查询当前用户下的所有索引

select 'alter index '|| index_name ||' rebuild tablespace
tablespacename;' from user_indexes;

c. 在当前用户下将查询结果批处理执行即可！

6. 通过v$sqlarea,v$sql查询最占用资源的查询

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

v$sqlarea,v$sql

-----------------------
从V$SQLAREA中查询最占用资源的查询
select b.username username,a.disk_reads reads,

a.executions exec,a.disk_reads/decode(a.executions,0,1,a.executions) rds_exec_ratio,

a.sql_text Statement

from v$sqlarea a,dba_users b

where a.parsing_user_id=b.user_id

and a.disk_reads > 100000

order by a.disk_reads desc;
用buffer_gets列来替换disk_reads列可以得到占用最多内存的sql语句的相关信息。

V$SQL是内存共享SQL区域中已经解析的SQL语句。

列出使用频率最高的5个查询：
select sql_text,executions

from (select sql_text,executions,

rank() over

(order by executions desc) exec_rank

from v$sql)

where exec_rank <=5;

消耗磁盘读取最多的sql top5：

select disk_reads,sql_text

from (select sql_text,disk_reads,

dense_rank() over

(order by disk_reads desc) disk_reads_rank

from v$sql)

where disk_reads_rank <=5;

找出需要大量缓冲读取（逻辑读）操作的查询：
select buffer_gets,sql_text

from (select sql_text,buffer_gets,

dense_rank() over

(order by buffer_gets desc) buffer_gets_rank

from v$sql)

where buffer_gets_rank<=5;

7. Oracle锁表查询

最近遇到这样一个问题，操作一个表，发现被人锁定了，于是查询谁锁定的表，发现多人锁定，安全起见，不能全部kill，于是用一下语句判定，谁锁定，谁等待。

SELECT /*+ rule */ lpad(' ',decode(l.xidusn ,0,3,0))||l.oracle_username User_name，

s.LOCKWAIT,s.status,s.machine,s.terminal,

o.owner,o.object_name,o.object_type,s.sid,s.serial#

FROM v$locked_object l,dba_objects o,v$session s

WHERE l.object_id=o.object_id AND lower(object_name)='tb_offer'

AND l.session_id=s.sid

ORDER BY o.object_id,xidusn DESC；

如果发生了锁等待，我们可能更想知道是谁锁了表而引起谁的等待

以上的语句可以查询到谁锁了表，而谁在等待。

以上查询结果是一个树状结构，如果有子节点，则表示有等待发生。

如果想知道锁用了哪个回滚段，还可以关联到V$rollname，其中xidusn就是回滚段的USN

找出谁锁定的记录，kill掉就行了。

alter system kill session '133,3506'; (其中133是SID，3506是SERIAL#)

--以下几个为相关表

SELECT * FROM v$lock;

SELECT * FROM v$sqlarea;

SELECT * FROM v$session;

SELECT * FROM v$process ;

SELECT * FROM v$locked_object;

SELECT * FROM all_objects;

SELECT * FROM v$session_wait;