RE: Who is using my datafile (what's in segments)

From: Mark W. Farnham <>
Date: Wed, 9 Jul 2008 08:25:56 -0400
Message-ID: <00b201c8e1be$f1115560$>

That is both a summary of the total space and where the first piece (header) is for things (objects) that actually take up their own space. Notice, for example, that individual sequences do not have an entry in dba_segments, because they are stored in seq$.

Check out the view(s) for the details, or look at one of the many fine dictionary posters put out by third party vendors (usually for free).

-----Original Message-----
From: [] On Behalf Of Yechiel Adar
Sent: Wednesday, July 09, 2008 2:27 AM
Subject: Re: Who is using my datafile

I am a little confused here.

I thought that dba_segments contain information about space allocated to objects and dba_extents contain the information about the space allocation within each segments.
Now I find that:
select * from dba_segments where header_file = 7; return no rows while:
select * from dba_extents where file_id = 7; return some rows.

So, I am switching to check dba_extents to clear space in datafiles.

What is the purpose of dba_segments?

Adar Yechiel
Rechovot, Israel

Yechiel Adar wrote:
> I have a RAC on windows.
> Oracle 9206.
> I have five datafiles that have nothing in them.
> I mean that select * from sys.seg$ where file# between 6 and 11 return
> nothing.
> When I tried to decrease the size of the datafiles I got: the file
> contain data beyond the space I want to decrease to.
> I thought that maybe there are some temporary segments but all the
> users use temp as their temporary tablespace.


Received on Wed Jul 09 2008 - 07:25:56 CDT

Original text of this message