Comments on: Reporting Space-Wasting Objects in Oracle

By: Paul

Paul — Tue, 01 Mar 2011 03:46:06 +0000

Hi Marc,

Nice procedure btw.

You might find this useful. Sometimes tables aren’t full of empty blocks but mostly empty blocks (fs4_blocks in dbms_space terms).

select owner,segment_name,round(fs4_blocks/total_blocks,2)*100 as “Blocks75to100free” from segment_space_stats where fs4_blocks/total_blocks > 0.5 and total_bytes > 100*1024*1024;

By: Catherine

Catherine — Thu, 25 Feb 2010 13:54:47 +0000

Hi Marc
Thank you very much. Your response make it clearly for me :-)

By: Marc

Marc — Wed, 24 Feb 2010 14:37:36 +0000

Hi Catherine,

As I understand it, unused_blocks (generated with the unused_space procedure) show the total blocks in the segment that are allocated to segment extents but have NEVER been used. Data deletion will not add blocks to the unused_blocks nor the unformatted_blocks.

You can look at this post from Tom Kyte for his demonstration. I just had a look at that post and he basically created a similar procedure to the one I posted here, but he had done so way before me…

http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:231414051079

Also, in his post he has this explanation about the unformatted blocks:

“unformatted blocks are blocks that are available for immediate use (below the true high water mark) but haven’t yet had any data. when the table says “i’m full”, we pull a bunch of blocks down into the table from above the HWM and they would all be unformatted until you use them.”

Hope this helps.
Marc

By: Catherine

Catherine — Wed, 24 Feb 2010 12:54:27 +0000

Hi Marc. Could you give same explain about the difference between unformatted_blocks and unused_blocks? I’m confused. I don’t know which blocks had free space because of deleting, so are under HWM and which blocks had never data and are above HWM.

thx

By: comfeng

comfeng — Wed, 04 Mar 2009 14:39:16 +0000

Thank you for your article!

By: Marcio

Marcio — Fri, 18 Jul 2008 01:48:56 +0000

I already knew the dbms_space package but, your script is very useful to us and also very didactic.
Great work!

Regards,

Marcio Lima.

By: David Edwards

David Edwards — Wed, 16 May 2007 17:12:10 +0000

Thanks for the heads-up, Don. Fixed now.

By: Don Seiler

Don Seiler — Wed, 16 May 2007 16:24:57 +0000

I finally got a chance to read this, and the links to your scripts both give me a 404!

By: Marc

Marc — Wed, 02 May 2007 15:24:56 +0000

I’m glad you like it Raj,

The unit is MB, same as the other columns.

Enjoy!
Marc

By: Raj Jamadagni

Raj Jamadagni — Wed, 02 May 2007 13:26:08 +0000

Nice Script Marc,

but what unit you had in mind for values in “estimated savings” (the rightmost) column?
blocks? kb? mb?

BTW I had put dbms_space call inside a pipelined function, so it becomes easy to put it in a subquery if needed.

Raj