RE: Block question
- From: "Paul Harrison" <cure@xxxxxxxxxxxxx>
- To: <mark.brinsmead@xxxxxxxxx>
- Date: Fri, 27 Feb 2015 15:00:38 -0600
Hi Mark,
&block_value = 159440
Why would I need the below as the other block #s within the extent(0) are not
included in the the dba_extents view?
159440 BETWEEN 159440AND (159440 + 8)
segment_name extent_id file_id block_id bytes blocks
CUST 0 1 159440 65536
8
CUST 1 1 159464 65536
8
Thank You,
Paul
From: oracle-l-bounce@xxxxxxxxxxxxx [mailto:oracle-l-bounce@xxxxxxxxxxxxx] On
Behalf Of MARK BRINSMEAD
Sent: Friday, February 27, 2015 2:30 PM
To: cure@xxxxxxxxxxxxx
Cc: ORACLE-L
Subject: Re: Block question
No.
The purpose of this query is (appears to be) to identify the segment (or the
extent of the segment) containing a particular block. This is something you
would probable want to do, for example, when your alertlog reports that block
#12345 in file #7 has been corrupted.
In order for &block_value = blockid to work (with any reliability),
DBA_EXTENTS would need have a row for each and every block in each and every
extent in the entire database. Not only would that not be proper normalization
of the data, it would be incredibly wasteful of storage.
DBA_EXTENTS reports only the first block and the number of blocks in the extent
(recall that extents are always a contiguous range of blocks within a single
datafile). To find the extent (or object) containing a block that interests
you, you need check whether it is within a range.
On Fri, Feb 27, 2015 at 3:21 PM, Paul Harrison <cure@xxxxxxxxxxxxx> wrote:
Hi Team,
I came upon the below on the internet.
" ( &block_value BETWEEN block_id AND ( block_id + blocks ) )" <-- I don't
understand how this comes into the equation. Shouldn't it just be &block_value
= <value> ?
List an Object and Object Type via a Given File and Block ID.
--
-- List an Object and Object Type via a Given File and Block ID.
--
SET PAUSE ON
SET PAUSE 'Press Return to Continue'
SET PAGESIZE 60
SET LINESIZE 300
COLUMN segment_name FORMAT A24
COLUMN segment_type FORMAT A24
SELECT segment_name, segment_type, block_id, blocks
FROM dba_extents
WHERE
file_id = &file_no
AND
( &block_value BETWEEN block_id AND ( block_id + blocks ) )
/
Thanks,
Paul
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