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Export reduced database size. [message #360210] Thu, 20 November 2008 01:23 Go to next message
IBNHUSSAIN
Messages: 39
Registered: December 2007
Location: INDIA
Member
Hi,

I exported/imported a full database using pipes from Sun OS to HP-UX.

The export completed successfully without warnings and import as well but with minor warnings which we can ignore.

But when i check the source database.

SQL> select sum(bytes)/(1024*1024*1024) from dba_segments;

SUM(BYTES)/(1024*1024*1024)
---------------------------
                 104.613647



Target database after import.

SQL> select sum(bytes)/(1024*1024*1024) from dba_segments;

SUM(BYTES)/(1024*1024*1024)
---------------------------
                 83.3868408


Could you explain me why it has been reduced? or
Is there any problem with my export and import?


Thanks in advance.

[Updated on: Thu, 20 November 2008 01:24]

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Re: Export reduced database size. [message #360219 is a reply to message #360210] Thu, 20 November 2008 01:50 Go to previous messageGo to next message
Michel Cadot
Messages: 64103
Registered: March 2007
Location: Nanterre, France, http://...
Senior Member
Account Moderator
Different block size
Different tablespace parameters
Different segment parameters
Different row insertion order
Different row life
...

Regards
Michel
Re: Export reduced database size. [message #360260 is a reply to message #360219] Thu, 20 November 2008 04:00 Go to previous messageGo to next message
IBNHUSSAIN
Messages: 39
Registered: December 2007
Location: INDIA
Member
Thanks Michel for your reply.

Could you please explain me with some more details.

Because db_block_size is same for both the databases.
i.e. 8192

Source:

SQL> show parameter block

NAME                                 TYPE        VALUE
------------------------------------ ----------- -----------------------------
db_block_buffers                     integer     85000
db_block_checking                    boolean     FALSE
db_block_checksum                    boolean     TRUE
db_block_size                        integer     8192
db_file_multiblock_read_count        integer     8
SQL>


Target:
SQL> show parameter block

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
db_block_buffers                     integer     0
db_block_checking                    string      FALSE
db_block_checksum                    string      TRUE
db_block_size                        integer     8192
db_file_multiblock_read_count        integer     8


Regarding other parameters you mentioned, Could you provide me any sql that shows me the differences on these instances.

Thanks & Best Regards
Re: Export reduced database size. [message #360279 is a reply to message #360260] Thu, 20 November 2008 04:44 Go to previous messageGo to next message
Michel Cadot
Messages: 64103
Registered: March 2007
Location: Nanterre, France, http://...
Senior Member
Account Moderator
I meant there are so many reasons to have different sizes that you can't know.
The most important ones are the 2 last ones that brinsg to rows life.

Regards
Michel
Re: Export reduced database size. [message #360336 is a reply to message #360210] Thu, 20 November 2008 08:20 Go to previous message
joy_division
Messages: 4640
Registered: February 2005
Location: East Coast USA
Senior Member
In addition to Michel's reply:

Different extent allocation type/size
Sparse storage in SOURCE database due to deletions over time

Many more. I'd ignore it unless you find missing objects.
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