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Difference between dba_extents and dba_segments [message #61983] Tue, 15 June 2004 22:45 Go to next message
Sanjay
Messages: 236
Registered: July 2000
Senior Member
when I take information of bytes and blocks allocated to an object from dba_extents and dba_segments I get the same information. I want to know the difference between both the views.

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Re: Difference between dba_extents and dba_segments [message #61989 is a reply to message #61983] Wed, 16 June 2004 00:49 Go to previous message
Daljit Singh
Messages: 290
Registered: October 2003
Location: Texas
Senior Member
Hi,

As u know that segment is a collection of multiple or single extents. So DBA_EXTENTS will show the total bytes allocated to an extent and that extent is belong to which segment. And DBA_SEGMENTS will show the total bytes allocated by a single segment. And thats why the sum of bytes of both of the views for same segment will be same.

If u see carefully u will find multiple rows of a single segment in DBA_EXTENTS view which indicate the number of extents in that segment, whereas in DBA_SEGMENTS u will find only one row per segment bcz it show the overall picture of a complete segment.

Daljit Singh

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