RE: ** import tuning
- From: "Marquez, Chris" <cmarquez@xxxxxxxxxxxxxxxx>
- To: <mgogala@xxxxxxxxxxxxxxxxxxxx>, <ajoshi977@xxxxxxxxx>
- Date: Wed, 8 Jun 2005 14:46:48 -0400
>> _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@xxxxxxxxxxxxx on behalf of Mladen Gogala
Sent: Wed 6/8/2005 2:30 PM
To: ajoshi977@xxxxxxxxx
Cc: egorst@xxxxxxxxx; oracle-l@xxxxxxxxxxxxx
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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