Oracle-L: RE: Space Remaining in Current Extent

From: Thomas Day <tday6_at_csc.com>
Date: Tue, 27 May 2003 12:40:04 -0800
Message-ID: <F001.005A39AF.20030527124004@fatcity.com>

I'm not sure if this is any help:
--block_e_byte.sql

/*
The Oracle blocks used by a given table and the corresponding bytes. */
--Inspired by a posting by Rick_Cale_at_teamhealth.com on ORACLE-L
--Requires one parameter, the table name.
SELECT COUNT (DISTINCT
DBMS_ROWID.ROWID_BLOCK_NUMBER(rowid)||
DBMS_ROWID.ROWID_RELATIVE_FNO(rowid))
"Blocks Used" FROM &&1;
SELECT COUNT (DISTINCT
DBMS_ROWID.ROWID_BLOCK_NUMBER(a.rowid)|| DBMS_ROWID.ROWID_RELATIVE_FNO(a.rowid))
* b.value
"Bytes Used" FROM &&1 a, v$parameter b where name = 'db_block_size' group by b.value;

There should be some way to decode rowid to tell you which blocks are used in a given extent --- I just don't have the time or resources to do it right now.

                                                                                                                                       
                      DENNIS WILLIAMS                                                                                                  
                      <DWILLIAMS               To:      Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>                    
                      @LIFETOUCH.COM>          cc:                                                                                     
                      Sent by: root            Subject: RE: Space Remaining in Current Extent                                          
                                                                                                                                       
                                                                                                                                       
                      05/27/2003 03:39                                                                                                 
                      PM                                                                                                               
                      Please respond                                                                                                   
                      to ORACLE-L

Kevin - Since you haven't received any replies, here goes. Within an extent, Oracle uses blocks. I haven't seen a way to find the used space within a block. There are methods to find the number of empty blocks underneath the high water mark. Analyze does that, but you've ruled that out. It might help if you could explain what you are trying to accomplish. Other ideas are:

Write a program that will scan the table, read each row and count the bytes as it reads it. This would be very accurate, but time-consuming.
An approximate answer could be arrived at by doing an analyze and getting average row length. This shouldn't change much unless some operation is performed that would alter that. Then by getting the number of rows in the table you could get a very close estimate of the table size at any time.

Dennis Williams
DBA, 80%OCP, 100% DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com

-----Original Message-----

Sent: Tuesday, May 27, 2003 11:15 AM
To: Multiple recipients of list ORACLE-L

Hey guys;
Does anyone know where I can look to find the space remaining in an individual extent ?? I know that you can get the freespace from dba_free_space but that seems to be based only on unallocated extents. I have been asked to find out, down to the byte, how much free space is available ..... on the fly (which means not only after every analyze)

Any suggestions ??? I am sure Oracle has a table with the information somewhere .

Thanks

Kevin
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Author: Kevin Lange
INET: klange_at_ppoone.com

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Author: Thomas Day
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