RE: ** import tuning

>> _disable_logging
>> by setting this parameter, you are losing redo log protection.
>> If the instance crashes...your database is terminally corrupt.
Yes I agree 100%.
I have been burned using this parameter while leaving it set and then the SA shutdown the server. My database was dead!
I was *lucky* to be able recover my database using unsupported methods.

>>it does speed import quite a bit,
>>but it definitely is a dangerous parameter. Very dangerous.
Yes, I only use it to speed the IMPort on a non production database and un-set it! *BUT* even unsetting _disable_logging can be challenging...you must cycle through all the redo logs after unsetting and before you can go into archive log mode. I'm not recommending this parameter for normal business use.

Oracle has many features, and options (that's why we love it). I (try my best) to never use parameters, features, and options I do not understand...even basic new parameters, features, and options. There are no "silver bullets" in the Oracle world and most parameters, features, and options have a down side!

hth

Chris Marquez
Oracle DBA

-----Original Message-----
From: oracle-l-bounce_at_freelists.org on behalf of Mladen Gogala Sent: Wed 6/8/2005 2:30 PM
To: ajoshi977_at_yahoo.com
Cc: egorst_at_gmail.com; oracle-l_at_freelists.org Subject: Re: ** import tuning  

A Joshi wrote:

>Thanks to Egor for your help. Also to Mladen Marquez, Chris, Michael McMullen, Mark
>Is "_disable_logging to be set at instance level? In init.ora? Or can I re create tablespace with nologging option expect the same benefit.
>

Nologging option disables writing to redo logs. Nothing is written to redo logs. Absolutely nothing. WMD.
That is true for all operations, not just for direct mode inserts. Commit basically just marks the transaction record "committed". That happens in SGA. Of course, by setting this parameter, you are losing redo log protection. If the instance crashes while this parameter is in effect, your database is terminally corrupt. Take a cold backup before you do that.

It is an instance parameter and cannot be set on the session level. As I've previously said, it does speed import quite a bit, but it definitely is a dangerous parameter. Very dangerous.

-- 
Mladen Gogala
Oracle DBA
Ext. 121


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