Maclean’s Oracle Database Tech Blog Archives

kgl simulator，共享池simulator以及缓冲simulator相关解释

KGL是 kernel general Library cache manager,它管理library cache中的对象包括游标，PL/SQL存储过程，表的定义等等。 KGL simulator 评估当缓存大于目前情况的获益。其通过将flush out出library cache的object的hash code保存至kgl simulator的 hash 列表中，以造成object似乎仍在缓存中的假象，方便其统计相关的数据。

October 5, 2009
11g内存管理新特性的internal表现

-rw-r—– 1 oracle oinstall 16777216 9月 27 18:59 ora_T11_327680_119 -rw-r—– 1 oracle oinstall 0 9月 27 18:59 ora_T11_327680_12 可以看到启动后出现的16MB文件形式共享内存中部分大小为０，这些块被选出当发生内存交换时来被’destory’．使用pmap工具仍可以看到该部分影射，而实际上已经被Oracle释放了．现在我们加大pga，观察其交换情况．

September 27, 2009
PHP使用mail函数发送邮件标题乱码问题

PHP程序使用mail()函数发送邮件的时候，标题中文的话会出现乱码。所以可以先对其进行base64编码。

September 27, 2009
Oracle内部错误ORA-07445[kpopfr()+339] [SIGFPE]一例

以上循环执行一段时间后session会被关闭，告警日志中出现 ORA-07445: exception encountered: core dump [kpopfr()+339] [SIGFPE] [Integer divide by zero][0x002327FF5] [] []的记录。没有在9i版本上测试，不能确定其影响。

September 23, 2009
Restoring a user's original password

WARNING ======= The method described in this article is not officially supported by development, therefore when you get errors using this procedure support cannot file a bug for it. Please make no mistakes when setting the HEX value with the VALUES keyword as bad values may cause internal errors. This undocumented feature exists to support…

September 21, 2009
Oracle中RMAN恢复目录性能问题研究

Tracing the RMAN client Ideally, set debug trace on the RMAN command line and execute a simplied script to illustrate the problem eg %rman target / catalog usr/pw@ log rman.log trace rman.trc debug run { allocate channel t1 type sbt parms=(…………); backup database plus archivelog all; } Otherwise trace only the command that you are…

September 15, 2009
Oracle中如何追踪savepoint

我们可以通过trace找出会话中自上次commit以来所有的savepoint保存点，要阅读这些trace内容你需要有user_dump_dest目录的相关权限。 SQL> oradebug setmypid; 已处理的语句 SQL> SQL> SQL> insert into system.linktest values(2); 已创建 1 行。 SQL> savepoint a; 保存点已创建。 SQL> insert into system.linktest values(3); 已创建 1 行。 SQL> savepoint b; 保存点已创建。 SQL> insert into system.linktest values(4); 已创建 1 行。 SQL> savepoint d; 保存点已创建。 SQL> oradebug event immediate trace name savepoints level 1；已处理的语句 SQL> oradebug…

September 15, 2009
OPT_PARAM Hint

Applies to: Oracle Server – Enterprise Edition – Version: 10.2.0.1 to 10.2.0.3 – Release: 10.2 to 10.2 Information in this document applies to any platform. Goal This article is explains the new optimizer hint “OPT_PARAM” introduced in 10g R2. Solution “OPT_PARAM” is a new optimizer hint introduced in 10g Release 2. This hint behaves the…

September 11, 2009
如何找出Oracle中需要或值得重建的索引

This script determines whether an index is a good candidate for a rebuild or for a bitmap index. All indexes for a given schema or for a subset of schema’s are analyzed (except indexes under SYS and SYSTEM) Instructions Execution Environment: <SQL, SQL*Plus, iSQL*Plus> Access Privileges: Requires DBA privileges in order to be executed. Usage:…

September 10, 2009
Oracle在硬件领域正式向IBM宣战

这份开战宣言表明了Oracle在硬件领域发展的决心，以及同IBM争霸的勇气。两家同样以销售著名的公司（相对SUN等技术著名公司），将在未来几年内为我们展示新一轮的IT航母兼并战。

September 10, 2009