12.07.05

用FlashBack query恢复误删数据

Posted in Oracle备份恢复 at 11:58 pm by dosql

用法示例:

(1) 找出删除前的数据:

SELECT ename, sal FROM emp AS OF TIMESTAMP (SYSTIMESTAMP – INTERVAL ‘6’ MINUTE)
WHERE ename = ‘ALLEN’; Read the rest of this entry »

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IBM 360+EXP 300双机安装手记

Posted in Oracle管理 at 10:08 am by David.Guo

IBM 360+EXP 300双机安装手记

郭岳(GYTYL)
本人文档，如需转载，请注明出处！
一：硬件环境主机：IBM Eserver X360两台（带硬盘两块）盘柜：IBM EXP300盘柜（带硬盘8块）
二：软件环境操作系统：WINDOWS 2000 ADVANCE SERVER RAID MANAGER:7.10.18 数据库：ORACLE 8.1.7.4 Read the rest of this entry »

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12.06.05

Oracle817通用连接方式连接sql server2000

Posted in Oracle管理 at 4:33 pm by David.Guo

Oracle817通用连接方式连接sql server2000

本人文档，如需转载，请注明出处！

本来不准备写这个blog的，但是今天在群上看到一个兄弟database link链接失败，想想可能有用，就丢上来了。

0：前言

透明网关（Transparent Gateways）透明网关使用Oracle提供的特定网关程序来设置代理，例如连接SQL Server则必须要有SQL Transparent Gateway for SQL Server。
通用连接（Generic Connectivity）通用连接又分为ODBC连接和OLE DB连接两种，其连接方法和透明网关没有本质区别，只不过通用连接是和数据库一起提供的功能，你不需要向Oracle购买相关的透明网关程序。 Read the rest of this entry »

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12.05.05

2005圣诞晚会中奖

Posted in 其他内容 at 10:51 am by dosql

星期五是公司的圣诞晚会. 本来以为要开车去, 就喝不了酒了. 好在后来单位里的一个MM告诉我可以要taxi sheet, 赶紧去要了两张.

晚上等老婆回家, 再换衣服, 已经5点多了才叫taxi. 路上自然又是堵车, 到晚会地点时已经快7点了. 晚会是6点开始, 按以往的规矩是6点到7点随意喝. 我想这下完了, 还是没酒喝. 没想到今年改成了发酒券, 没有时间限制了.

吃饭是没啥意思. 老外的东西, 人多了就吃不到好的. 没想到吃完了, 我还有一个惊喜: 我居然中奖了! 这在我的记忆中可没发生过几回, 是不是我也该考虑买点6/49了?

想起gytyl最近也中奖, 明年看来是个好年头.

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12.04.05

Sybase虚惊一场

Posted in David.Guo的心情随笔 at 1:39 pm by David.Guo

昨天下午,杭州风大雨大
正陪同学在西湖边晃
某个地方的项目兄弟告诉我
Sybase数据库连接不上去了
这个我就有点晕了
那里可是IBM的小机加上阵列
作了HA的,怎么会连接不上列
等到兄弟过去看了
发现ping都ping不到主机了
这下有点麻烦了

Read the rest of this entry »

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买彩中奖记

Posted in David.Guo的心情随笔 at 1:33 pm by David.Guo

对于彩票
我一直都在买,
不过每期也就是10块钱,
不象别人那样还要选号,研究
每次都是机选
也正因为这样
所以从来没有中过奖
想不到
这次同学过来
居然中了5块钱的奖
不知道是不是好预兆,哈哈
说不定
下次就是5000000了
期待哟.

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Rebuild index的探讨

Posted in Oracle管理 at 12:07 pm by dosql

这几天看了几篇关于rebuild index的文章, 才发现大部分情况下是没有必要rebuild的. 好在我还没有勤快到设了job定期做rebuild, 要不然也成了被tom骂的一类人了.

参见:
http://asktom.oracle.com/pls/ask/f?p=4950:8:2029594428707830766::NO::F4950_P8_DISPLAYID,F4950_P8_CRITERIA:2913600659112

http://www.actoug.org.au/Downloads/oracle_index_internals.pdf

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12.02.05

enqueue 等待事件探究

Posted in Oracle优化, Brotherxiao's at 12:29 pm by bachelor

Enqueues are another type of locking mechanism used in Oracle.
An enqueue is a more sophisticated mechanism which permits several concurrent
processes to have varying degree of sharing of “known” resources. Any object
which can be concurrently used, can be protected with enqueues. A good example
is of locks on tables. We allow varying levels of sharing on tables e.g.
two processes can lock a table in share mode or in share update mode etc.
One difference is that the enqueue is obtained using an OS specific
locking mechanism. An enqueue allows the user to store a value in the lock,
i.e the mode in which we are requesting it. The OS lock manager keeps track
of the resources locked. If a process cannot be granted the lock because it
is incompatible with the mode requested and the lock is requested with wait,
the OS puts the requesting process on a wait queue which is serviced in FIFO.
Another difference between latches and enqueues is that
in latches there is no ordered queue of waiters like in enqueues. Latch
waiters may either use timers to wakeup and retry or spin (only in
multiprocessors). Since all waiters are concurrently retrying (depending on
the scheduler), anyone might get the latch and conceivably the first one to
try might be the last one to get.
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