敗家貓

如沒有加 online 的話，這時的table的lock為mode4
如有加的話，這時的table的lock為mode2
最大的好處就是有加online的話，就可不影響對這個table的dml操作，但會需要雙倍建立index的空間

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SGA, System Global Area---可以被所以PROCESS訪問。
PGA, Process Global Area—單個PROCESS（thread）私有。
UGA會包括在其中之一里
UGA, User Global Area—SESSION私有，shared server的時候在SGA，dedicated server的時候在PGA ...繼續閱讀

測試目地:得知 temp table跟一般 table 在做處理時產生的 redo size 的差別多少

oracle: 9.2.0.6.0
archivelog:開起
os: Red Hat Enterprise Linux AS release 4 (Nahant Update 1) ...繼續閱讀

主要內容如下:

Configure and use flashback database Use the Flashback drop feature to recover dropped tables Use the Flashback Versions Query feature to retrieve row history information Use the Flashback transaction query fasture to audit or recover from transactions Use the Flashback table feature to recover tables to a point in time 官方網址 http://download-west.oracle.com/docs/cd/B13789_01/appdev.101/b10795/adfns_fl.htm#1011142

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在測驗10g的flashback時發生ORA-38760的解決方法

錯誤訊習:ORA-38774: 無法停用媒體復原 - 已啟用倒溯資料庫

處理流程:
SQL> select flashback_on from v$database;

FLASHBACK_ON
------------------------------------
YES

SQL> alter database flashback off;

已更改資料庫. ...繼續閱讀

小記一下
from metalink not<286363.1>

When a truncate/drop is issued,

1.the foreground first acquires the "RO" enqueue in exclusive mode,
2.then cross instance calls (or one call if it is a single object) are issued
(the "CI" enqueue is acquired for cross instance call)
3.The CKPT processes on each of instances requests the DBWR to write
the dirty buffers to the disk and invalidate all the clean buffers.
4. After DBWR finishes writing, the foreground process releases the RO
enqueue.


來源:
http://www.itpub.net/viewthread.php?tid=921802&extra=&page=2

Converting timestamps between timezomes

Problem
=======
There are many reasons why you might want to convert a 'timestamp' from 1
timezone to another. For example you might have traditionaly stored all times
as GMT times, but you want to know what those timestamps are in Paris.
Because different timezones have different rules regarding the changing
of Daylight Saving Time (or no DST at all) this is not as trivial as it might
seem at first.
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小記一下，方便以後查

http://www.oracle.com/technology/pub/articles/smiley-11gr1-install.html?rssid=rss_otn_articles