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Home -> Community -> Mailing Lists -> Oracle-L -> RE: reattaching datafiles
Hi Doug,
Thanks for the reply. Incidentally, they did use to use re-cycled parchments, called palimpsests, in ancient times. There was a magazine article I read recently about some writings of Aristotle (or one of his students/descendants) being recovered. His manuscripts had been bleached and re-used by monks producing illustrated bibles - but his technology was superior, and he had used an ink that penetrated deeply into the page whereas the monks' ink just stuck to the surface, so in modern times, the original writing could be restored. Now *that's* a database recovery!
So let's say I had a database, created a tablespace with one datafile, created a user with a default of that tablespace, did a bunch of transactions, committed them, then dropped the tablespace. I know that the datafile is "compatible" with the instance, because it came from there. The datafile contains all the data from the transactions. Is it just useless now? Can the data be recovered back into the original instance from this datafile?
I know I could get it back by recovering from the last hotbackup and rolling forward with archived redo logs, but it just seems a little strange that datafiles can be "orphaned" like this... Hmmm.
Cheers,
g
-----Original Message-----
Sent: 02 November 2001 14:05
To: Guy Hammond; Multiple recipients of list ORACLE-L
Guy,
The 'drop tablespace' command does a number of items. It purges the
data
dictionary of all references to that tablespace, removes the file
information
from the control file, closes the datafile(s) and releases them back to
the
operating system. All that being said, if you then want to reuse the
datafile
as a new tablespace then you have to wipe it. The simplest reason being
that
you may be using it in a database with a different block size. Look at
it this
way, if you were starting to write a new book, would you use a notepad
of erased
paper? If you did there might end up being some very interesting side
notes
running around.
Dick Goulet
____________________Reply Separator____________________ Author: "Guy Hammond" <guy.hammond_at_avt.co.uk> Date: 11/2/2001 5:40 AM
Hello all,
When a tablespace is dropped, the datafile is left on the disk. What exactly is the drop tablespace command doing, and is there a way to get that datafile and "re-attach" to a new tablespace in some way? For example, creating a tablespace using that datafile, but without wiping it, as the "reuse" clause does?
Thanks,
g
--
Guy Hammond
AVT Technologies
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Please see the official ORACLE-L FAQ: http://www.orafaq.com
--
Author: Guy Hammond
INET: guy.hammond_at_avt.co.uk
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