ORACLE 常用的ｓｑｌ

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 "% USED",(C.BYTES*100)/A.BYTES "% FREE"
  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、查看当前所有对象

SQL> select * from tab;

11、建一个和a表结构一样的空表

SQL> create table b as select * from a where 1=2;

SQL> create table b(b1,b2,b3) as select a1,a2,a3 from a where 1=2;

12、察看数据库的大小，和空间使用情况

SQL> col tablespace format a20
SQL> select b.file_id　　文件ID,
　　b.tablespace_name　　表空间,
　　b.file_name　　　　　物理文件名,
　　b.bytes　　　　　　　总字节数,
　　(b.bytes-sum(nvl(a.bytes,0)))　　　已使用,
　　sum(nvl(a.bytes,0))　　　　　　　　剩余,
　　sum(nvl(a.bytes,0))/(b.bytes)*100　剩余百分比
　　from dba_free_space a,dba_data_files b
　　where a.file_id=b.file_id
　　group by b.tablespace_name,b.file_name,b.file_id,b.bytes
　　order by b.tablespace_name
　　/
　　dba_free_space --表空间剩余空间状况
　　dba_data_files --数据文件空间占用情况

13、查看现有回滚段及其状态

SQL> col segment format a30
SQL> SELECT SEGMENT_NAME,OWNER,TABLESPACE_NAME,SEGMENT_ID,FILE_ID,STATUS FROM DBA_ROLLBACK_SEGS;

14、查看数据文件放置的路径

SQL> col file_name format a50
SQL> select tablespace_name,file_id,bytes/1024/1024,file_name from dba_data_files order by file_id;

15、显示当前连接用户

SQL> show user

16、把SQL*Plus当计算器

SQL> select 100*20 from dual;

17、连接字符串

SQL> select 列1||列2 from 表1;
SQL> select concat(列1,列2) from 表1;

18、查询当前日期

SQL> select to_char(sysdate,'yyyy-mm-dd,hh24:mi:ss') from dual;

19、用户间复制数据

SQL> copy from user1 to user2 create table2 using select * from table1;

20、视图中不能使用order by，但可用group by代替来达到排序目的

SQL> create view a as select b1,b2 from b group by b1,b2;

21、通过授权的方式来创建用户

SQL> grant connect,resource to test identified by test;

SQL> conn test/test

22、．监控事例的等待：
         select event,sum(decode(wait_time,0,0,1)) prev, sum(decode(wait_time,0,1,0)) curr,count(*)
from v$session_wait
group by event order by 4;

23、监控表空间的I/O比例：
select df.tablespace_name name,df.file_name "file",f.phyrds pyr,f.phyblkrd pbr,f.phywrts pyw,
f.phyblkwrt pbw
from v$filestat f,dba_data_files df
where f.file#=df.file_id
24、.监空文件系统的I/O比例：
select substr(a.file#,1,2) "#",substr(a.name,1,30) "name",a.status,a.bytes,
b.phyrds,b.phywrts
from v$datafile a,v$filestat b
where a.file#=b.file#
25、在某个用户下找所有的索引：
select user_indexes.table_name, user_indexes.index_name,uniqueness, column_name
from user_ind_columns, user_indexes
where user_ind_columns.index_name = user_indexes.index_name
and user_ind_columns.table_name = user_indexes.table_name
order by user_indexes.table_type, user_indexes.table_name,
user_indexes.index_name, column_position;
26、. 监控 SGA 的命中率
select a.value + b.value "logical_reads", c.value "phys_reads",
round(100 * ((a.value+b.value)-c.value) / (a.value+b.value)) "BUFFER HIT RATIO"
from v$sysstat a, v$sysstat b, v$sysstat c
where a.statistic# = 38 and b.statistic# = 39
and c.statistic# = 40;
27、 监控 SGA 中字典缓冲区的命中率
select parameter, gets,Getmisses , getmisses/(gets+getmisses)*100 "miss ratio",
(1-(sum(getmisses)/ (sum(gets)+sum(getmisses))))*100 "Hit ratio"
from v$rowcache
where gets+getmisses <>0
group by parameter, gets, getmisses;
28、监控 SGA 中共享缓存区的命中率，应该小于1%
select sum(pins) "Total Pins", sum(reloads) "Total Reloads",
sum(reloads)/sum(pins) *100 libcache
from v$librarycache;
select sum(pinhits-reloads)/sum(pins) "hit radio",sum(reloads)/sum(pins) "reload percent"
from v$librarycache;
29、 显示所有数据库对象的类别和大小

select count(name) num_instances ,type ,sum(source_size) source_size ,
sum(parsed_size) parsed_size ,sum(code_size) code_size ,sum(error_size) error_size,
sum(source_size) +sum(parsed_size) +sum(code_size) +sum(error_size) size_required
from dba_object_size
group by type order by 2;
30、 监控 SGA 中重做日志缓存区的命中率，应该小于1%
SELECT name, gets, misses, immediate_gets, immediate_misses,
Decode(gets,0,0,misses/gets*100) ratio1,
Decode(immediate_gets+immediate_misses,0,0,
immediate_misses/(immediate_gets+immediate_misses)*100) ratio2
FROM v$latch WHERE name IN ('redo allocation', 'redo copy');
31、 监控内存和硬盘的排序比率，最好使它小于 .10，增加 sort_area_size
SELECT name, value FROM v$sysstat WHERE name IN ('sorts (memory)', 'sorts (disk)');
32、 监控当前数据库谁在运行什么SQL语句
SELECT osuser, username, sql_text from v$session a, v$sqltext b
where a.sql_address =b.address order by address, piece;
33. 监控字典缓冲区
SELECT (SUM(PINS - RELOADS)) / SUM(PINS) "LIB CACHE" FROM V$LIBRARYCACHE;
SELECT (SUM(GETS - GETMISSES - USAGE - FIXED)) / SUM(GETS) "ROW CACHE" FROM V$ROWCACHE;
SELECT SUM(PINS) "EXECUTIONS", SUM(RELOADS) "CACHE MISSES WHILE EXECUTING" FROM V$LIBRARYCACHE;
后者除以前者,此比率小于1%,接近0%为好。

SELECT SUM(GETS) "DICTIONARY GETS",SUM(GETMISSES) "DICTIONARY CACHE GET MISSES"
FROM V$ROWCACHE

34. 找ORACLE字符集
select * from sys.props$ where name='NLS_CHARACTERSET';
35. 监控 MTS
select busy/(busy+idle) "shared servers busy" from v$dispatcher;
此值大于0.5时，参数需加大
select sum(wait)/sum(totalq) "dispatcher waits" from v$queue where type='dispatcher';
select count(*) from v$dispatcher;
select servers_highwater from v$mts;
servers_highwater接近mts_max_servers时，参数需加大
36. 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;
37.查看碎片程度高的表
SELECT segment_name table_name , COUNT(*) extents
FROM dba_segments WHERE owner NOT IN ('SYS', 'SYSTEM') GROUP BY segment_name
HAVING COUNT(*) = (SELECT MAX( COUNT(*) ) FROM dba_segments GROUP BY segment_name);
38. 表、索引的存储情况检查
select segment_name,sum(bytes),count(*) ext_quan from dba_extents where
tablespace_name='&tablespace_name' and segment_type='TABLE' group by tablespace_name,segment_name;
select segment_name,count(*) from dba_extents where segment_type='INDEX' and owner='&owner'
group by segment_name;
39、找使用CPU多的用户session
12是cpu used by this session
select a.sid,spid,status,substr(a.program,1,40) prog,a.terminal,osuser,value/60/100 value
from v$session a,v$process b,v$sesstat c
where c.statistic#=12 and c.sid=a.sid and a.paddr=b.addr order by value desc;
40.监控log_buffer的使用情况：(值最好小于1%，否则增加log_buffer 的大小)
select rbar.name,rbar.value,re.name,re.value,(rbar.value*100)/re.value||'%' "radio"
from v$sysstat rbar,v$sysstat re
where rbar.name='redo buffer allocation retries'
and re.name='redo entries';
41、查看运行过的SQL语句：
SELECT SQL_TEXT
FROM V$SQL