Re: Shrink Table: IEstimating Rollback Space
Date: Fri, 17 Oct 2008 08:40:36 -0700
Again , does that include the time taken to rebuild the indexes.
On 10/17/08 8:27 AM, "Tim Gorman" <tim_at_evdbt.com> wrote:
> Insert operations are *ALWAYS* faster (i.e. using direct-path) and more
> scalable (i.e. using parallel) than update/delete operations; direct-path
> operations pretty much eliminate undo, and NOLOGGING option for direct-path
> can pretty much eliminate redo. Rebuild is essentially an insert operation,
> same as move. So, move/rebuild will absolutely take less elapsed time than
> shrink (unless the environment is short of CPU/IO resources); the only thing
> in favor of ALTER TABLE ... SHRINK SPACE is the online capability.
> It's the age-old "speed vs flexibility" trade-off that permeates just about
> everything in computing. It's nice to have a choice.
> Ian MacGregor wrote:
>> Re: Shrink Table: IEstimating Rollback Space Move requires rebuilding of the >> indexes. Iım nrt sure it will be quicker. >> Ian >> >> >> On 10/16/08 6:46 PM, "rjamya" <rjamya_at_gmail.com> <mailto:rjamya_at_gmail.com> >> wrote: >> >> >>> i haven't see a formula but there is a metalink note that says for larger >>> tables ' alter table move' might be better since shrink is insert (in the >>> beginning) and delete (from tail end) operation and hence takes longer and >>> generated more redo. >>> >>> Raj >>> >>> On Thu, Oct 16, 2008 at 4:52 PM, Ian MacGregor <ian_at_slac.stanford.edu> >>> <mailto:ian_at_slac.stanford.edu> wrote: >>> >>>> I have a 450 GB table with 150 GB of free space. I'd like to shrink the >>>> table, but I'm not sure how much rollback will be needed. Is there a >>>> formula? One that accounts for the indexes as well? >>>> >>>> Ian MacGregor >>>> SLAC National Accelerator Laboratory >>> >>> -- http://www.freelists.org/webpage/oracle-lReceived on Fri Oct 17 2008 - 10:40:36 CDT