Re: Fragmentation with restore multiple channels
- From: Dragutin Jastrebic <orahawk@xxxxxxxxx>
- To: oracle-l@xxxxxxxxxxxxx
- Date: Tue, 4 Sep 2012 23:41:34 +0200
Hi,
I can give 2 logical reasons why it simply cannot work
this way (I mean rman multiple channel restore leading to fragmentation)
1) If this "fragmentation" really happens, does it mean that
our database has new data density, new data clustering, perhaps more
index
levels and so on? If so, one would need do gather statistics
immediately after opening the database since old
statistics are not accurate anymore . More than that, we could think that
after any Rman restore, we might gather new statistics "just in case"
Oracle suggests to gather the statistics after massive data load,
perhaps afterdata reorganisation (rebuild ,shrink etc) and so on
With data pump & exp/imp utility you have parameters to control
statistics
behaviour while importing etc
But with Rman, has anyone ever heard of such a practice ?
2) If this was true then the cloning of database with Rman could not be
called cloning anymore
since the new created destination database is different from the source
database
In the case of the physical standby database ,If we have used rman to
copy the
database and this fragmentation took place,the blocks on standby database
are not the exact copy of primary database and the recovery process will
not work
So it simply does not make sense. Rman is just copying blocks while
restoring. (I don't
see neither how differential & cumulative backups can contribue to any
kind of fragmentation)
Regards,
Dragutin
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