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segment size [message #397292] Thu, 09 April 2009 23:22 Go to next message
sundarfaq
Messages: 235
Registered: October 2007
Location: Chennai
Senior Member
Hi all,
I have inserted 2 lacks records into bank_transaction table. After that, I have checked size of the bank transaction table it shows 312.34MB. I have verified from below query.
SELECT SUM (BYTES) / 1024 / 1204
FROM user_segments
WHERE segment_name = 'BANK_TRANSACTION';

After, I have deleted one lacks records into this table. I have checked size of this segments it shows 312.34MB. I have exported this table using exp utility. The size of the dump size only 122MB. I have imported this dump file into other database. After I have checked the size of the table is 312MB. Actually the size of the segment should be 122 mb + datafiles header size and other allocated size 50MB. Totally, it must be 170mb. But It shows 312MB. I don't know why it varies?

Why size of the segments is high compare than dump file size?


Thanks,
Michael
Re: segment size [message #397295 is a reply to message #397292] Thu, 09 April 2009 23:28 Go to previous messageGo to next message
BlackSwan
Messages: 25035
Registered: January 2009
Location: SoCal
Senior Member
> Actually the size of the segment should be 122 mb + datafiles header size and other allocated size 50MB.
Prove it.
> Totally, it must be 170mb.
Prove it.
Re: segment size [message #397296 is a reply to message #397292] Thu, 09 April 2009 23:29 Go to previous message
Michel Cadot
Messages: 64103
Registered: March 2007
Location: Nanterre, France, http://...
Senior Member
Account Moderator
It depends on tablespace parameters, segment parameters, data.
If you have 2500 bytes of data in each row and 4K block then you lose 1500 bytes for each row.

Regards
Michel
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