RE: "Deallocate Unused" not bringing down the HWM in tables
- From: Feighery Raymond <Raymond.Feighery@xxxxxxxxxxxxx>
- To: "'oracle-l@xxxxxxxxxxxxx'" <oracle-l@xxxxxxxxxxxxx>
- Date: Wed, 10 Mar 2004 14:00:00 -0000
EMPTY_BLOCKS refers to the number of never used blocks in the table, that is
the blocks within the segment above the HWM. This will not be affected
directly by deletes.
Moving a table within its own tablespace will reset the HWM, which will
actually increase not reduce the number of empty blocks (assuming unchanged
storage parameters). The number of empty blocks is then affected by table
storage parameters.
"When I look the empty_blocks, for some tables it has not yet released the
space."
Can you clarify this?
Ray
-----Original Message-----
From: vidya kalyanaraman [mailto:vidya.kalyanaraman@xxxxxxxxxx]
Sent: Wednesday, March 10, 2004 6:51 AM
To: oracle-l@xxxxxxxxxxxxx
Subject: "Deallocate Unused" not bringing down the HWM in tables
Hi All
I am trying to reclaim the wasted space (huge deletes), which are above the
HWM. I had analysed the table before and got the "empty_blocks" details
from dba_tables.
I am using the following query,
alter table tab1 deallocate unused;
and then to bring down the HWM,
alter table tab1 move tablespace AR_DATA; ---- Moved within the same
tablespace
and then I had rebuilt all the corresponding indexes.
As a last step, I had coalesced the tablespace.
Next day (because SMON is not going to clear it up immediately), I had
analyzed the tables again and got the "empty_blocks" details from
dba_tables.
When I look the empty_blocks, for some tables it has not yet released the
space.
Am I missing any steps? I searched Metalink, but it looks like I have
covered everything that needs to be.
I have one more question. To really reclaim the space, do I have to move the
table out of its own tablespace ?
Any thoughts are most welcome.
Thanks and Regards
Vidya
--
Vidya Kalyanaraman
Phone: +91 80 5108 4285
Fax:+91 80 5506749
Principal Consultant
iTech Practice
Oracle Solution Services India
PBC software Park
Level 1 and 2
No. 9 Hosur Road
Bangalore - 560 029
India
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