Re: Disable logging in tablespace vs using hidden parameter _disable_logging
- From: Li-Shan Cheng <exriscer@xxxxxxxxx>
- To: Juan Carlos Reyes Pacheco <juancarlosreyesp@xxxxxxxxx>
- Date: Thu, 2 Feb 2006 19:48:52 +0100
Well the problem is set NOLOGGING to tablespaces does not give you better
performance UNLESS your index logging attribute is set to NOLOG in the
origin. But then again you should import withour indexes anyways. Importing
data will ALWAYS generate redo since it´s plain insert statements and not
insert append.
I doubt very much you can even save any time by set to nologging at
tablespace level.
If you can get the _disable_logging effect without using the parameter do
you think why this would even exist....?
If you want fast import you can do several things, first of all get all the
DDL statements
1. import only data
2. create indexes with the DDL and adding NOLOGGING and parallel clauses
3. create the constraints but keep them DISABLED
4. Enable the constraints by setting parallel degree at table level, by
doing so parallel executions can be used
Finally which is obvious restore the objects attributes, parallel degree,
logging etc.
This has been a very succesful method for me a few months ago when I was
migrating several databases from Solaris to HPUX.
On 2/2/06, Juan Carlos Reyes Pacheco <juancarlosreyesp@xxxxxxxxx> wrote:
>
> HI Li, thanks I know that, I RTFM,
>
> It is an open question about how to get the _disable_logging effect
> without using that parameter.
>
> What I'm asking is about applying no logging to all tablespaces before
> import?
> Compared to setting _disable_logging?
> I don't know if some one knows about improvements.
> For example
> "setting nologgin to all tablespace I saved 1% of time, but I set this
> other parameter too, etc.."
> And any other comment about reducing logging activity without using
> the _disable_logging parameter.
> :)
>
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