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Oracle专家高级编程学习笔记[1]
添加时间: 2008-4-28 23:01:04 作者: Oracle指导 阅读次数:24 来源: http://www.d9soft.com
Expert one-on-one oracle是Oracle专家Thomas Kyte的大作,洋洋大观,总共有1329页,啃起来颇费力气.故作此笔记,记录精华所在.
一.准备工作
1.建立基本调试环境
Create demo schema(建立演示模式)
sqlplus>start $ORACLE_HOME/sqlplus/demo/demobld.sql
2.建立login.sql
define_editor=vi
set serveroutput on size 1000000
set trimspool on
set long 500
set linesize 100
set pagesize 9999
column plan_plus_exp format a80
column global_name new_value gname
select lower(user)||'@'||decode(global_name,'WEBDB.FANYAMIN.NET','webdb',global_name) global_name from global_name;
set sqlprompt '&gname>'
set termout on
3.在sqlplus中配置AutoTrace
1)cd $ORACLE_HOME/rdbms/admin
log into sqlplus as system(connect system/manager@webdb)
run @utlxplan
run create public synonym plan_table for plan_table;
run grant all on plan_table to public;
2)
cd $ORACLE_HOME/sqlplus/admin
log into sqlplus as sys(connect sys/change_on_install@webdb)
run @plustrce
run grant plustrace to public;
二.内容
1.开发成功的Oracle应用程序
一条简单秘诀
if(possible) 就用单条SQL语句完成
else if(possible) 用plsql程序
else if(possible) 用java存储过程
else if(possible) 用C外部过程
else 考虑是否真有必要这样做
两个指导方针
1)不要在MTS下运行长事务<45s
2)使用绑定变量
system@webdb>alter system flush shared_pool;
system@webdb>set timing on
执行这两个sql文件,一比较,发现使用绑定变量后,速度快多了
--bindtest1.sql, did not use bind variable
declare
type rc is ref cursor;
l_rc rc;
l_dummy all_objects.object_name%type;
l_start number default dbms_utility.get_time;
begin
for i in 1..1000
loop
open l_rc for
'select object_name from all_objects where object_id='||i;
fetch l_rc into l_dummy;
close l_rc;
end loop;
dbms_output.put_line(round((dbms_utility.get_time-l_start)/100,2)||'seconds...');
end;
/
--bindtest2.sql, use bind variable
declare
type rc is ref cursor;
l_rc rc;
l_dummy all_objects.object_name%type;
l_start number default dbms_utility.get_time;
begin
for i in 1..1000
loop
open l_rc for
'select object_name from all_objects where object_id=:x'
using i;
fetch l_rc into l_dummy;
close l_rc;
end loop;
dbms_output.put_line(round((dbms_utility.get_time-l_start)/100,2)||'seconds...');
end;
/
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