ORACLE DBA常用語句和指令碼
一, 常用到的設定環境引數的語句
設定SCOTT/TIGER的DEMO
執行@ORACLE_HOME/sqlplus/demo/demobld.sql (響應的demodrop.sql.是DROP SCOTT的指令碼)
做一個登陸用的login.sql
define _editor=vi
set serveroutput on size 1000000 使DBMS_OUTPUT有效.
set trimspool on SPOOL不會以定長來控制,而是以空格來控制
set long 5000 LONG或CLOG 顯示的長度
set linesize 100
set pagesize 9999 每9999行後列印HEAD
column plan_plus_exp format a80 autotrace後explain plan output的格式
column global_name new_value gname
set termout off
define gname=idle
column global_name new_value gname
select lower(user) || || substr( global_name, 1,
decode( dot, 0, length(global_name), dot-1) ) global_name
from (select global_name, instr(global_name,'.') dot from global_name );
set sqlprompt '&gname> '
set termout on
set trimspool on; 去除重定向（spool）輸出每行的拖尾空格，預設為off
得到的提示符. >
二, 常用到的DBA指令碼
Runstats 比較兩個作相同事情的方法的優劣點。本包統計三個值，一個是時間（不重要，由於手工執行，而且偏差較大），二，使用記憶體方面，三，LATCH。
開發人員經常在自己的PC上裝DB,然後進行開發,這些指令碼的目的就是讓開發人員可以觀察自己的SQL是如何執行的以及效率如何.
create or replace view stats
as select 'STAT...' || a.name name, b.value
from v$statname a, v$mystat b
where a.statistic# = b.statistic#
union all
select 'LATCH.' || name, gets
from v$latch;
create global temporary table run_stats
( runid varchar2(15),
name varchar2(80),
value int )
on commit preserve rows;
create or replace package runstats_pkg
as
procedure rs_start; --執行操作之前
procedure rs_middle; --執行第一個操作之後
procedure rs_stop( p_difference_threshold in number default 0 ); --結束 --p_difference_threshold 控制多大差別才予以輸出。
end;
create or replace package body runstats_pkg
as
g_start number; --全域性變數。
g_run1 number;
g_run2 number;
procedure rs_start --清空以前的統計資訊
is
begin
delete from run_stats; ---清空
insert into run_stats
select 'before', stats.* from stats;
g_start := dbms_utility.get_time;
end;
procedure rs_middle --記錄第一個SQL執行時間,STATISTIC,LATCH
is
begin
g_run1 := (dbms_utility.get_time-g_start);
insert into run_stats
select 'after 1', stats.* from stats;
g_start := dbms_utility.get_time;
end;
procedure rs_stop(p_difference_threshold in number default 0)
is
begin
g_run2 := (dbms_utility.get_time-g_start);
dbms_output.put_line
( 'Run1 ran in ' || g_run1 || ' hsecs' );
dbms_output.put_line
( 'Run2 ran in ' || g_run2 || ' hsecs' );
dbms_output.put_line
( 'run 1 ran in ' || round(g_run1/g_run2*100,2) ||
'% of the time' );
dbms_output.put_line( chr(9) );
insert into run_stats
select 'after 2', stats.* from stats;
dbms_output.put_line
( rpad( 'Name', 30 ) || lpad( 'Run1', 10 ) ||
lpad( 'Run2', 10 ) || lpad( 'Diff', 10 ) );
for x in
( select rpad( a.name, 30 ) ||
to_char( b.value-a.value, '9,999,999' ) ||
to_char( c.value-b.value, '9,999,999' ) ||
to_char( ( (c.value-b.value)-(b.value-a.value)), '9,999,999' ) data
from run_stats a, run_stats b, run_stats c
where a.name = b.name
and b.name = c.name
and a.runid = 'before'
and b.runid = 'after 1'
and c.runid = 'after 2'
and (c.value-a.value) > 0
and abs( (c.value-b.value) - (b.value-a.value) )
> p_difference_threshold
order by abs( (c.value-b.value)-(b.value-a.value))
) loop
dbms_output.put_line( x.data );
end loop;
dbms_output.put_line( chr(9) );
dbms_output.put_line
( 'Run1 latches total versus runs -- difference and pct' );
dbms_output.put_line
( lpad( 'Run1', 10 ) || lpad( 'Run2', 10 ) ||
lpad( 'Diff', 10 ) || lpad( 'Pct', 8 ) );
for x in
( select to_char( run1, '9,999,999' ) ||
to_char( run2, '9,999,999' ) ||
to_char( diff, '9,999,999' ) ||
to_char( round( run1/run2*100,2 ), '999.99' ) || '%' data
from ( select sum(b.value-a.value) run1, sum(c.value-b.value) run2,
sum( (c.value-b.value)-(b.value-a.value)) diff
from run_stats a, run_stats b, run_stats c
where a.name = b.name
and b.name = c.name
and a.runid = 'before'
and b.runid = 'after 1'
and c.runid = 'after 2'
and a.name like 'LATCH%'
)
) loop
dbms_output.put_line( x.data );
end loop;
end;
end;
/
測試
SQL> create table wwm as select * from all_objects where 1=2;
表已建立。
SQL> create table wwm2 as select * from all_objects where 1=2;
表已建立。
SQL> exec runstats_pkg.rs_start;
PL/SQL 過程已成功完成。
SQL> insert into wwm select * from all_objects;
已建立34750行。
SQL> exec runstats_pkg.rs_middle;
PL/SQL 過程已成功完成。
然後用第二種方法，一行一行地插入。
SQL> begin
2 for x in (select * from all_objects)
3 loop
4 insert into wwm2 values x;
5 end loop;
6 commit;
7 end;
8 /
---------------( create procedure p( ENAME in varchar2 )
as
begin
for x in ( select * from emp where ename = ENAME ) loop
Dbms_output.put_line( x.empno );
end loop;
end;
-----------------
SQL> exec runstats_pkg.rs_stop(1000000)
Run1 ran in 3558 hsecs
Run2 ran in 14263 hsecs
run 1 ran in 24.95% of the time
Name Run1 Run2 Diff
STAT...session pga memory 0 4,040,516 4,040,516
STAT...session pga memory max 0 4,064,632 4,064,632
STAT...session pga memory max 0 4,064,632 4,064,632
STAT...session pga memory 0 4,106,052 4,106,052
STAT...redo size 3,920,896########## 8,291,688
STAT...redo size 3,920,896########## 8,352,408
Run1 latches total versus runs -- difference and pct
Run1 Run2 Diff Pct
305,006 1,462,079 1,157,073 20.86%
三, Mystat 統計某操作之前和之後的變化。
Mystat.sql指令碼捕捉初始值
set echo off
set verify off
column value new_val V
define S="&1"
輸入 1 的值: redo size --可以輸入不同的值來判斷不同的指標
set autotrace off
select a.name, b.value
from v$statname a, v$mystat b
where a.statistic# = b.statistic#
and lower(a.name) like '%' || lower('&S')||'%'
/
NAME VALUE
-----------------------------
redo size 16408460
set echo on
中間做需要統計的操作。
1* update wwm set object_name=lower(object_name)
SQL> /
已更新34750行。
mystat2指令碼報告異同點。
set echo off
set verify off
select a.name, b.value V, to_char(b.value-&V,'999,999,999,999') diff
from v$statname a, v$mystat b
where a.statistic# = b.statistic#
and lower(a.name) like '%' || lower('&S')||'%'
NAME V DIFF
------------------------------------
redo size 26028120 9,619,660
可以看到這次UPDATE產生了9,619,660 bytes of redo.
四, Show_space 統計SEGMENT的空間使用具體情況。
create or replace procedure show_space
( p_segname in varchar2, --SGEMENT的NAME
p_owner in varchar2 default user, --默任是當前使用者
p_type in varchar2 default 'TABLE', --SEGMENT 的TYPE
p_partition in varchar2 default NULL ) --PARTITION的NAME
-- this procedure uses authid current user so it can query DBA_*
-- views using privileges from a ROLE, and so it can be installed
-- once per database, instead of once per user who wanted to use it
authid current_user
as
l_free_blks number;
l_total_blocks number;
l_total_bytes number;
l_unused_blocks number;
l_unused_bytes number;
l_LastUsedExtFileId number;
l_LastUsedExtBlockId number;
l_LAST_USED_BLOCK number;
l_segment_space_mgmt varchar2(255);
l_unformatted_blocks number;
l_unformatted_bytes number;
l_fs1_blocks number; l_fs1_bytes number;
l_fs2_blocks number; l_fs2_bytes number;
l_fs3_blocks number; l_fs3_bytes number;
l_fs4_blocks number; l_fs4_bytes number;
l_full_blocks number; l_full_bytes number;
-- inline procedure to print out numbers nicely formatted
-- with a simple label
procedure p( p_label in varchar2, p_num in number )
is
begin
dbms_output.put_line( rpad(p_label,40,'.') ||
to_char(p_num,'999,999,999,999') );
end;
begin
-- this query is executed dynamically in order to allow this procedure
-- to be created by a user who has access to DBA_SEGMENTS/TABLESPACES
-- via a role as is customary.
-- NOTE: at runtime, the invoker MUST have access to these two
-- views!
-- this query determines if the object is an ASSM object or not
begin
execute immediate
'select ts.segment_space_management
from dba_segments seg, dba_tablespaces ts
where seg.segment_name = :p_segname
and (:p_partition is null or
seg.partition_name = :p_partition)
and seg.owner = :p_owner
and seg.tablespace_name = ts.tablespace_name'
into l_segment_space_mgmt
using p_segname, p_partition, p_partition, p_owner;
exception
when too_many_rows then
dbms_output.put_line
( 'This must be a partitioned table, use p_partition => ');
return;
end;
-- if the object is in an ASSM tablespace, we must use this API
-- call to get space information, otherwise we use the FREE_BLOCKS
-- API for the user-managed segments
if l_segment_space_mgmt = 'AUTO'
then
dbms_space.space_usage
( p_owner, p_segname, p_type, l_unformatted_blocks,
l_unformatted_bytes, l_fs1_blocks, l_fs1_bytes,
l_fs2_blocks, l_fs2_bytes, l_fs3_blocks, l_fs3_bytes,
l_fs4_blocks, l_fs4_bytes, l_full_blocks, l_full_bytes, p_partition);
p( 'Unformatted Blocks ', l_unformatted_blocks );
p( 'FS1 Blocks (0-25) ', l_fs1_blocks );
p( 'FS2 Blocks (25-50) ', l_fs2_blocks );
p( 'FS3 Blocks (50-75) ', l_fs3_blocks );
p( 'FS4 Blocks (75-100)', l_fs4_blocks );
p( 'Full Blocks ', l_full_blocks );
else
dbms_space.free_blocks(
segment_owner => p_owner,
segment_name => p_segname,
segment_type => p_type,
freelist_group_id => 0,
free_blks => l_free_blks);
p( 'Free Blocks', l_free_blks );
end if;
-- and then the unused space API call to get the rest of the
-- information
dbms_space.unused_space
( segment_owner => p_owner,
segment_name => p_segname,
segment_type => p_type,
partition_name => p_partition,
total_blocks => l_total_blocks,
total_bytes => l_total_bytes,
unused_blocks => l_unused_blocks,
unused_bytes => l_unused_bytes,
LAST_USED_EXTENT_FILE_ID => l_LastUsedExtFileId,
LAST_USED_EXTENT_BLOCK_ID => l_LastUsedExtBlockId,
LAST_USED_BLOCK => l_LAST_USED_BLOCK );
p( 'Total Blocks', l_total_blocks );
p( 'Total Bytes', l_total_bytes );
p( 'Total MBytes', trunc(l_total_bytes/1024/1024) );
p( 'Unused Blocks', l_unused_blocks );
p( 'Unused Bytes', l_unused_bytes );
p( 'Last Used Ext FileId', l_LastUsedExtFileId );
p( 'Last Used Ext BlockId', l_LastUsedExtBlockId );
p( 'Last Used Block', l_LAST_USED_BLOCK );
end;
SQL> desc show_space
PROCEDURE show_space
引數名稱 型別 輸入/輸出預設值?
------------------------------ ----------------------- ------ --------
P_SEGNAME VARCHAR2 IN
P_OWNER VARCHAR2 IN DEFAULT
P_TYPE VARCHAR2 IN DEFAULT
P_PARTITION VARCHAR2 IN DEFAULT
ASSM和user space managed tablespaces得到的結果不同,以下用user space managed tablespaces來說明
SQL> exec show_spacE('WWM');
Free Blocks............................. 2
Total Blocks............................ 5,120
Total Bytes............................. 41,943,040
Total MBytes............................ 40
Unused Blocks........................... 13
Unused Bytes............................ 106,496
Last Used Ext FileId.................... 1
Last Used Ext BlockId................... 46,473
Last Used Block......................... 115
FULL BLOCKS: full表示在沒有變化之前不會再被分配出去。
Total Blocks, Total Bytes, Total MBytes: 整個分配給此SEGMENT的空間。
Unused Blocks, Unused Bytes:分配給SEGMENT，但是還沒有使用，也就是說在HWM之上的空閒塊。
Last Used Ext FileId: 最後一個extent所在的FILE ID.
Last Used Ext BlockId: 最後一個EXTENT 的BEGIN BLOCK ID.
FS1 Blocks–FS4 Blocks: 例如,0-25,表示在0-25%之間的空塊.
做一個大表,以供測試使用
create table big_table
as
select rownum id, a.*
from all_objects a
where 1=0
/
alter table big_table nologging;
insert /*+ append */
into big_table
select rownum, a.*
from all_objects a;
已建立29645行。
1 insert /*+ append */
2 into big_table
3 select rownum+29646, a.*
4* from all_objects a
SQL> /
已建立29645行。
alter table big_table add constraint
big_table_pk primary key(id)
1 begin
2 dbms_stats.gather_table_stats
3 ( wnname => 'SYSTEM',
4 tabname => 'BIG_TABLE',
5 method_opt => 'for all indexed columns',
6 cascade => TRUE );
7* end;
五, 繫結變數與非繫結變數
閱讀本章可以參考我的 BIND VARIABLE
http://sunmoonking.spaces.live.com/blog/cns!E3BD9CBED01777CA!175.entry
測試表
create table t ( x int );
繫結變數
create or replace procedure proc1
as
begin
for i in 1 .. 10000
loop
execute immediate
'insert into t values ( :x )' using i;
end loop;
end;
/
非繫結變數
create or replace procedure proc2
as
begin
for i in 1 .. 10000
loop
execute immediate
'insert into t values ( '||i||')';
end loop;
end;
/
SQL> exec runstats_pkg.rs_start;
PL/SQL 過程已成功完成。
SQL> exec proc1
PL/SQL 過程已成功完成。
SQL> exec runstats_pkg.rs_middle;
PL/SQL 過程已成功完成。
SQL> exec proc2
PL/SQL 過程已成功完成。
SQL> exec runstats_pkg.rs_stop(1000); --差別大於1000的才輸出
Run1 ran in 1622 hsecs
Run2 ran in 4378 hsecs
run 1 ran in 37.05% of the time
Name Run1 Run2 Diff
STAT...bytes received via SQL* 387 1,690 1,303
STAT...bytes sent via SQL*Net 276 1,798 1,522
STAT...parse count (hard) 5 10,009 10,004
…………………………………………………………………………….
Run1 latches total versus runs -- difference and pct
Run1 Run2 Diff Pct
313,680 1,625,995 1,312,315 19.29%
PL/SQL 過程已成功完成。
可以看到PRO2基本上是PRO1的三倍,也就是說解析時間佔完整執行完一條語句所耗時間的2/3，會多佔用LATCH.可見,儘量減少硬解析能明顯提高效能.
六,read-consistent
SQL> create table wwm as select * from all_users;
表已建立。
SQL> variable x refcursor
SQL> begin
2 open :x for select * from wwm;
3 end;
4 /
PL/SQL 過程已成功完成。
SQL> delete from wwm;
已刪除27行。
SQL> commit;
提交完成。
SQL> print x
USERNAME USER_ID
------------------------------------------------------------ ----------
CREATED
--------------
BI 60
07-6月 -06
。。。。。。。。。。。。。。。
注意，這是在一個SESSION裡做的實驗。現建立一個表WWM，再OPEN一個CURSOR，再DELETE表WWM，甚至COMMIT之後還是可以PRINT CURSOR的原來的內容。
但是，需要明白的是，在OPEN一個CURSOR的時候並不取得資料或把資料放到某個地方；而是在DELETE的時候才將你需要的資料給你保留到一個地方（UNDO SEGMENT或叫ROLLBACK SEGMENT）。
七, flashback query.
SCN 是ORACLE內部時鐘，
SQL> variable SCN number
SQL> exec :scn:=dbms_flashback.get_system_change_number
PL/SQL 過程已成功完成。
SQL> print scn
SCN
----------
1170636
SQL> select count(*) from wwm;
COUNT(*)
----------
0
SQL> desc wwm
名稱 是否為空? 型別
----------------------------------------- -------- ----------------------------
USERNAME NOT NULL VARCHAR2(30)
USER_ID NOT NULL NUMBER
CREATED NOT NULL DATE
SQL> insert into wwm select * from all_users;
已建立27行。
SQL> select count(*) from wwm;
COUNT(*)
----------
27
SQL> select count(*) from wwm as of scn :scn;
COUNT(*)
----------
0
SQL> commit;
提交完成。
SQL> select count(*) from wwm as of scn :scn;
COUNT(*)
----------
0
甚至，我們可以用一個SQL得到兩個SCN點的值
SQL> select * from (select count(*) from wwm),
2 (select count(*) from wwm as of scn :scn);
COUNT(*) COUNT(*)
---------- ----------
27 0
來自 “ ITPUB部落格 ” ，連結：http://blog.itpub.net/9399028/viewspace-686446/，如需轉載，請註明出處，否則將追究法律責任。
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