Re: Decyphering LMT space bitmap

Jeremiah,

Everything looks normal. Block #3 shows the first couple bytes as "FFFFFF3F0000000...". When you decipher "FFFFFF3F", you will see 30 (out of a possible 32) bits in those 4 bytes (a.k.a. 8 "nibbles") set to "1" instead of "0", indicating that those are used extents. Your COUNT(*) on DBA_SEGMENTS confirms exactly that number...

Looks pretty straightforward. Now, is your LMT using "UNIFORM SIZE" or "AUTOALLOCATE" (i.e. default)?

Thanks!

-Tim

• Original Message ----- To: "Multiple recipients of list ORACLE-L" <ORACLE-L_at_fatcity.com> Sent: Monday, April 08, 2002 1:44 PM

> Out of curiosity I decided I wanted to look at what composed the
> extent map in locally-managed tablespaces.
>
> I dumped the first 5 blocks of the tablespace's first datafile with
> 'alter system dump datafile ...' The results surprised me, as they
> appeared to consist of almost no data. The LMT in question contains a
> variety of segments and extents. How is the LMT bitmap organized?
>
> Start dump data blocks tsn: 1 file#: 2 minblk 1 maxblk 1
> Block 1 (file header) not dumped: use dump file header command
>
> Start dump data blocks tsn: 1 file#: 2 minblk 2 maxblk 2
> frmt: 0x02 chkval: 0x0000 type: 0x1d=KTFB Bitmapped File Space Header
> File Space Header Block:
> Header Control:
> RelFno: 2, Unit: 8192, Size: 524352, Flag: 1
> Initial Area: 3, Tail: 524292, First: 30, Free: 34
>
> Start dump data blocks tsn: 1 file#: 2 minblk 3 maxblk 3
> frmt: 0x02 chkval: 0x0000 type: 0x1e=KTFB Bitmapped File Space Bitmap
> File Space Bitmap Block:
> BitMap Control:
> RelFno: 2, BeginBlock: 5, Flag: 0, First: 30, Free: 128994
> FFFFFF3F00000000 0000000000000000 0000000000000000 0000000000000000
> 0000000000000000 0000000000000000 0000000000000000 0000000000000000
> 0000000000000000 0000000000000000 0000000000000000 0000000000000000
> .. all zeros
>
> Start dump data blocks tsn: 1 file#: 2 minblk 4 maxblk 4
> frmt: 0x02 chkval: 0x0000 type: 0x1e=KTFB Bitmapped File Space Bitmap
> File Space Bitmap Block:
> BitMap Control:
> RelFno: 2, BeginBlock: 1056964613, Flag: 0, First: 0, Free: 129024
> 0000000000000000 0000000000000000 0000000000000000 0000000000000000
> 0000000000000000 0000000000000000 0000000000000000 0000000000000000
> 0000000000000000 0000000000000000 0000000000000000 0000000000000000
> .. all zeros
>
>
> FWIW:
>
> SQL> select count (*) from dba_extents where file_id = 2;
>
> COUNT(*)
> ----------
> 30
>
> SQL> select extent_management from dba_data_files df, dba_tablespaces
> ts where df.tablespace_name = ts.tablespace_name and file_id = 2;
>
> EXTENT_MAN
> ----------
> LOCAL
>
>
>
> --
> Jeremiah Wilton
> http://www.speakeasy.net/~jwilton
>
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.com
> --
> Author: Jeremiah Wilton
> INET: jwilton_at_speakeasy.net
>
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-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.com
-- 
Author: Tim Gorman
  INET: Tim_at_SageLogix.com

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