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where are the 0 to 8 block id's ? [message #234937]

Thu, 03 May 2007 09:00

Muhammad Ahmad
Messages: 30
Registered: November 2002

Member

hi,

SQL> select FILE_ID,EXTENT_ID,BLOCK_ID,BLOCKS from dba_extents where SEGMENT_NAME='EMP';

FILE_ID EXTENT_ID BLOCK_ID BLOCKS
---------- ---------- ---------- ----------
14 0 9 13
14 1 22 13
14 2 35 13
14 3 48 13
14 4 61 13
14 5 74 13
14 6 87 13
14 7 100 13
4 0 25 8

my question is where are the 0-8 block_id?

1. locally managed tablespace
2. segment space management manual
3.oracle 10g R1 (10.1.0.2.0)

Thanking you in advance.

Regards,

Ahmad.

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Re: where are the 0 to 8 block id's ? [message #234944 is a reply to message #234937]

Thu, 03 May 2007 09:20

Michel Cadot
Messages: 68733
Registered: March 2007
Location: Saint-Maur, France, https...

Senior Member
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Bitmaps to manage the tablespace.

Regards
Michel

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Re: where are the 0 to 8 block id's ? [message #235164 is a reply to message #234944]

Fri, 04 May 2007 03:54

Muhammad Ahmad
Messages: 30
Registered: November 2002

Member

Thanks Michel,

I have an idea about the BMBs (Bitmap Blocks) could use the 0 to 8 block ids, As per my observation Oracle resets the block-id on Per file basis -> is that means that the Oracle maintains the BMBs @ data-file level.

One more thing, Need your opinion about the space management option "segment space management AUTO" in locally managed tablespaces, how and where its information was maintained?

Thanks in advance,

Regards,
Ahmad.

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Re: where are the 0 to 8 block id's ? [message #235178 is a reply to message #235164]

Fri, 04 May 2007 04:18

Michel Cadot
Messages: 68733
Registered: March 2007
Location: Saint-Maur, France, https...

Senior Member
Account Moderator

1/ It's at datafile level: 1 (or more) bitmap per datafile

2/

SQL> select tablespace_name, segment_space_management from dba_tablespaces order by 1;
Tablespace        SEGMEN
----------------- ------
SYSAUX            AUTO
SYSTEM            MANUAL
TEMP              MANUAL
TEST              AUTO
TS_D01            AUTO
TS_I01            AUTO
UNDOTBS           MANUAL

7 rows selected.

Regards
Michel

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Re: where are the 0 to 8 block id's ? [message #235266 is a reply to message #235178]

Fri, 04 May 2007 10:22

Muhammad Ahmad
Messages: 30
Registered: November 2002

Member

Thanks Michel, for your quick response,

SQL> select tablespace_name, segment_space_management from dba_tablespaces order by 1;

Tablespace SEGMEN
----------------- ------
SYSAUX AUTO
SYSTEM MANUAL
TEMP MANUAL
TEST AUTO
TS_D01 AUTO
TS_I01 AUTO
UNDOTBS MANUAL

1) if SEGMENT_SPACE_MANAGEMENT contains "MANUAL" its means information is maintained in data dictionary tables (old-architecture), my Question is ->>> if it shows "AUTO" is this means that the information is maintained in "BMBs" { the same BMS's which are maintained @ datafile level for locally managed tablespaces} ?

Regards,

Ahmad

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Re: where are the 0 to 8 block id's ? [message #235273 is a reply to message #235266]

Fri, 04 May 2007 11:18

Michel Cadot
Messages: 68733
Registered: March 2007
Location: Saint-Maur, France, https...

Senior Member
Account Moderator

SEGMENT_SPACE_MANAGEMENT refers to space INSIDE the segments.
AUTO means space is managed by bitmap(s).
MANUAL means space is managed by freelist(s).
Nothing refers to dictionary tables.

Regards
Michel

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Re: where are the 0 to 8 block id's ? [message #235274 is a reply to message #235273]

Fri, 04 May 2007 11:24

sriram717
Messages: 48
Registered: February 2007
Location: UNITED KINGDOM

Member

Excellent Answer !!!

People generaly get confused with LMT and segmentspace management.

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Re: where are the 0 to 8 block id's ? [message #235618 is a reply to message #235273]

Mon, 07 May 2007 07:51

Muhammad Ahmad
Messages: 30
Registered: November 2002

Member

Thanks!

I am sorry michel i could not present my question clearly. . .

I want to know whether Oracle uses the same BMBs (Bitmap Blocks { 0 - 8 block id } to manage the bitmap for extent allocation (locally managed tablespaces) and the bitmap for segment level space management (segement space management auto) ?

Regards,

Ahmad.

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Re: where are the 0 to 8 block id's ? [message #235637 is a reply to message #235618]

Mon, 07 May 2007 09:18

Michel Cadot
Messages: 68733
Registered: March 2007
Location: Saint-Maur, France, https...

Senior Member
Account Moderator

No, they are different.
One type inside file header for extent management.
Another type inside segment header for segment space management.

Regards
Michel

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