Size of a dump file after import & export

  • From: "Justin Cave" <justin@xxxxxxxxxxx>
  • To: <oracle-l@xxxxxxxxxxxxx>
  • Date: Tue, 3 Aug 2004 06:13:55 -0600

We came across a 6.5 Gb dump file from Oracle 7.2.3 whose data has recently
become useful again.  I did a full import into a new database, only
to discover that some of the tables (1 schema worth) that were thought to be
in the export file didn't get imported.  The import log contained no errors
relating to those objects other than some invalid views that depended on the
missing tables.
As a sanity check, I figured I would do a full export of the newly imported
database, figuring that the new export file should be roughly equivalent in
size to the old export file size.  Unfortunately, after doing this sanity
check, the new export file is only 4.5 Gb.  As I see it, that implies that I
have either lost 2 Gb worth of data from the original import or something
has caused the export file size to shrink.
At this point, I'm rather hopeful that there exists a logical explanation
for the new export file being 30% smaller than the original export that
doesn't involve me losing data, but I'll be darned if I can find one.  I did
import the DMT 7.2.3 tablespaces into LMT tablespaces on the new instance,
but I don't see how that would cause this sort of change.
The import & export commands I'm using
mp system/<<pwd>>@<<db name>> log=<<dump file>>.log file=<<dump file>>.dmp
full=y ignore=y destroy=n constraints=n
exp system/<<pwd>>@<<db name>> full=y file=verify.dmp log=verify.log
Justin Cave
Distributed Database Consulting, Inc.

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