Re: Please a parameter to disable undo, like _disable_logging

  • From: Paul Drake <bdbafh@xxxxxxxxx>
  • To: tim@xxxxxxxxxxxxx
  • Date: Wed, 6 Oct 2004 09:25:06 -0400

Tim,

I"m not so sure that they are always dropped cleanly (smells like a bug)
win32, 10.1.0.3 Std Ed.
The test case is 
1 app tablespace of interest, 4MB uniform extents LMT, 6 datafiles of 1 GB each
2 tables, each an IOT
according to dba_segments, slightly less than 4 GB is allocated to the
2 segments.
according to dba_free_space, there is less than 20 MB free for the
entire tablespace.

using direct load against 2 IOTs, single load process.
Dark matter, perhaps?

I did see some sys-owned segments referred to in v$session_longops
like "SYS.ORA_TEMP_1_nnn" but those may have been for gathering of
statistics and not for maintenance of the (PK) index.

Paul


On Tue, 05 Oct 2004 22:18:32 -0600, Tim Gorman <tim@xxxxxxxxxxxxx> wrote:
> Direct-path or APPEND inserts do avoid undo, except for the space-management
> stuff in the data dictionary.
> 
> Direct-path loads data into TEMPORARY segments which, upon successful
> completion of the load (a.k.a. commit), are converted into DATA segments.
> Upon unsuccessful completion of the load (a.k.a. rollback), the TEMPORARY
> segments are simply dropped.
> 
> Look ma, no undo...
> 
> 
> 
> 
> on 10/5/04 9:33 PM, John Clarke at jclarke@xxxxxxxxxxxxxxx wrote:
> 
> > /*+ append */ disables redo, not undo (as does =5Fdisable=5Flogging).
> >
> > Array/bulk inserts will reduce the amount of undo you generate, so this =
> > method will help.  But you can't avoid undo altogether.
> >
> > At least you're not updating or deleting the 10,000,000 rows.
> >
> > John
> >
> > ----- Original Message -----
> > From: Juan Carlos Reyes Pacheco <jreyes@xxxxxxxxxxxxxxxx>
> > To: oracle-l@xxxxxxxxxxxxx
> > Sent: Tue,  5 Oct 2004 20:23:01 -0400
> > Subject: RE: Please a parameter to disable undo, like =5Fdisable=5Floggi=
> > ng
> >
> >
> >> thanks
> >> =20
> >> but /*+ append */ too bypasses undo, and if you set =5Fdisable=5Floggi=
> > ng you run
> >> the same risk, if you have a problem.
> >> I think for a test database could be acceptable. For example I'm tryin=
> > g to
> >> create a 10 000 000 records in my home for testing
> >> purposes, so this will be greatly welcome.
> >> I bet there should be a way.
> >> =20
> >> =20
> >> Juan Carlos Reyes Pacheco
> >> OCP
> 
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