yes a few seconds. that's why I said "without locking for any length of
time" and not "doesn't lock at all" :)
The point being that you can do the redef and still allow access to the
main table. Do a sync every once in a while while there is high volume
traffic, then do the finish when there is low volume
if you manually lock the table, then do the copy, it can take
significantly more time
- Mladen Gogala <mladen_at_wangtrading.com> wrote:
> I thought that finish_redef_table does lock table for a few seconds?
> On 01/09/2004 07:54:26 AM, Rachel Carmichael wrote:
> > Chris,
> >
> > Have you considered using dbms_redefinition for your second case?
> That
> > would allow you to reorg and swap the tables without locking for
> any
> > length of time.
> >
> > Rachel
> >
> >
> > --- chris_at_thedunscombes.f2s.com wrote:
> > > Richard,
> > >
> > > I agree there are a number of reasons for reorganising tables.
> LMTs
> > > remove the
> > > need to reorganise a tablespace but not to reorganise a table.
> Two
> > > further real-
> > > ilfe examples of table reorgs:
> > >
> > > 1) The purge programs have at last been written and run deleting
> data
> > > > 2 years
> > > old. The system's been running for 4 years. So in simple terms
> most
> > > of the
> > > tables are approx 50% empty. You need to reorg in this case.
> > >
> > > 2) A "transaction log" table is inserted to throughout the day
> and
> > > most of the
> > > night. A clear down processing job runs at the end of the day and
> > > deletes all
> > > the rows its processed, but more rows are being added. So the
> table
> > > is now < 1%
> > > full. Not good for FTS. So instead of a conventional reorg we
> > > implemented a
> > > nightly "table-swap". This meant locking the source table,
> copying
> > > it's
> > > contents to a replica empty single extent table, target table.
> The
> > > names of the
> > > target and source tables are swapped, hence "table-swap". The new
> > > source table
> > > is now available to the application and the original source is
> > > truncated and
> > > ready to be the target in 24 hrs time.
> > >
> > > Cheers,
> > >
> > > Chris Dunscombe
> > >
> > >
> > >
> > > Quoting Richard Foote <richard.foote_at_bigpond.com>:
> > >
> > > > MessageHi Thomas,
> > > >
> > > > Never say never (oh bugger, I've just gone and done it myself).
> > > >
> > > > A large table accessed via a FTS for various important
> reporting
> > > requirements
> > > > has permanently shrunk in size from 10G to 100M (say list of
> > > Informix
> > > > customers ;)
> > > >
> > > > Business requirements have changed and you need to add some
> columns
> > > to a
> > > > table resulting in mucho row migration.
> > > >
> > > > You were told (incorrectly) that rows would grow significantly
> > > after loading
> > > > (honestly) but now the 80 pctfree value you've set is causing
> > > problems for
> > > > other really important reports.
> > > >
> > > > There are of course other cases but you get my point ;)
> > > >
> > > > Cheers
> > > >
> > > > Richard
> > > > ----- Original Message -----
> > > > From: Mercadante, Thomas F
> > > > To: Multiple recipients of list ORACLE-L
> > > > Sent: Thursday, January 08, 2004 6:34 AM
> > > > Subject: RE: table reorganizations
> > > >
> > > >
> > > > Jolene,
> > > >
> > > > Tables should never *need* to be reorganized. This is an old
> > > falacy. If
> > > > you know how big a table is going to grow, say in a year, then
> > > place it in a
> > > > Locally Managed tablespace with extent sizes to hold enough
> data
> > > for one year
> > > > (say 1M).
> > > >
> > > > You should never have to reorganize a table.
> > > >
> > > > Tom Mercadante
> > > > Oracle Certified Professional
> > > > -----Original Message-----
> > > > From: Shrake, Jolene [mailto:JEShrake_at_Pella.com]
> > > > Sent: Wednesday, January 07, 2004 2:39 PM
> > > > To: Multiple recipients of list ORACLE-L
> > > > Subject: table reorganizations
> > > >
> > > >
> > > > What SQL statement do you use to identify tables that need
> > > > reorganization?
> > > >
> > > > How do you identify tables that are used in full table
> scans?
> > > How often
> > > > do you run this query?
> > > >
> > > > Thanks,
> > > > Jolene
> > > >
> > >
> > >
> > > Chris Dunscombe
> > >
> > > chris_at_thedunscombes.f2s.com
> > >
> > > -------------------------------------------------
> > > Everyone should have http://www.freedom2surf.net/
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> --
> Mladen Gogala
> Oracle DBA
> --
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> Author: Mladen Gogala
> INET: mladen_at_wangtrading.com
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Received on Fri Jan 09 2004 - 08:14:33 CST
