OraFAQ Forum: Performance Tuning

Home » RDBMS Server » Performance Tuning » DMT (oracle 9i, Windows XP)

Show: Today's Messages :: Polls :: Message Navigator
E-mail to friend

DMT [message #322073]

Thu, 22 May 2008 06:10

sdhanuka
Messages: 173
Registered: March 2008

Senior Member

Hey can anyone tell me about dictionary managed tablespaces or give me some useful links for the same. I have read a few articles but i have not understood what really is LMT & DMT.

Thanks

Report message to a moderator

Re: DMT [message #322075 is a reply to message #322073]

Thu, 22 May 2008 06:40

Michel Cadot
Messages: 68737
Registered: March 2007
Location: Saint-Maur, France, https...

Senior Member
Account Moderator

Database Concepts
Chapter 3 Tablespaces, Datafiles, and Control Files
Section Overview of Tablespaces
Subsection Managing Space in Tablespaces

When you have question like this, ALWAYS have a look at Database Concepts, 99% of answers are there.

Regards
Michel

[Updated on: Thu, 22 May 2008 06:41]

Report message to a moderator

Re: DMT [message #322079 is a reply to message #322075]

Thu, 22 May 2008 06:59

sdhanuka
Messages: 173
Registered: March 2008

Senior Member

Yes you are right. I have read that before. Still I was not able to follow what exactly do we mean by DMT & LMT.

Sad

Report message to a moderator

Re: DMT [message #322082 is a reply to message #322079]

Thu, 22 May 2008 07:06

Michel Cadot
Messages: 68737
Registered: March 2007
Location: Saint-Maur, France, https...

Senior Member
Account Moderator

What don't you understand?

Regards
Michel

Report message to a moderator

Re: DMT [message #322108 is a reply to message #322082]

Thu, 22 May 2008 09:19

sdhanuka
Messages: 173
Registered: March 2008

Senior Member

i mean i am getting really confused.

Report message to a moderator

Re: DMT [message #322111 is a reply to message #322108]

Thu, 22 May 2008 09:27

Michel Cadot
Messages: 68737
Registered: March 2007
Location: Saint-Maur, France, https...

Senior Member
Account Moderator

As I don't know what you don't understand, it is hard to explain you something.

DMT: extents are managed in dictionary tables sys.uet$, sys.fet$...
LMT: extents are managed with bitmap inside of the tablespace files.

Regards
Michel

Report message to a moderator

Re: DMT [message #322157 is a reply to message #322111]

Thu, 22 May 2008 11:49

sdhanuka
Messages: 173
Registered: March 2008

Senior Member

Ok..

when we do

select * from dict;

we do not get these dictionary tables.

Report message to a moderator

Re: DMT [message #322158 is a reply to message #322157]

Thu, 22 May 2008 11:53

BlackSwan
Messages: 26766
Registered: January 2009
Location: SoCal

Senior Member

sdhanuka wrote on Thu, 22 May 2008 09:49

Ok..

when we do

select * from dict;

we do not get these dictionary tables.

Correct.

SQL> desc dict
 Name                                      Null?    Type
 ----------------------------------------- -------- ----------------------------
 TABLE_NAME                                         VARCHAR2(30)
 COMMENTS                                           VARCHAR2(4000)

query DBA_TABLESPACES

Report message to a moderator

Re: DMT [message #322160 is a reply to message #322157]

Thu, 22 May 2008 11:58

Michel Cadot
Messages: 68737
Registered: March 2007
Location: Saint-Maur, France, https...

Senior Member
Account Moderator

"dict" does not show the whole catalog and dictionary, just "top level".

Regards
Michel

Report message to a moderator

Re: DMT [message #322164 is a reply to message #322158]

Thu, 22 May 2008 12:06

sdhanuka
Messages: 173
Registered: March 2008

Senior Member

alright

SQL> desc dba_tablespaces
 Name                                      Null?    Type
 ----------------------------------------- -------- -----------------------

 TABLESPACE_NAME                           NOT NULL VARCHAR2(30)
 BLOCK_SIZE                                NOT NULL NUMBER
 INITIAL_EXTENT                                     NUMBER
 NEXT_EXTENT                                        NUMBER
 MIN_EXTENTS                               NOT NULL NUMBER
 MAX_EXTENTS                                        NUMBER
 PCT_INCREASE                                       NUMBER
 MIN_EXTLEN                                         NUMBER
 STATUS                                             VARCHAR2(9)
 CONTENTS                                           VARCHAR2(9)
 LOGGING                                            VARCHAR2(9)
 FORCE_LOGGING                                      VARCHAR2(3)
 EXTENT_MANAGEMENT                                  VARCHAR2(10)
 ALLOCATION_TYPE                                    VARCHAR2(9)
 PLUGGED_IN                                         VARCHAR2(3)
 SEGMENT_SPACE_MANAGEMENT                           VARCHAR2(6)

so those tables are not a part of data dictionary??

Report message to a moderator

Re: DMT [message #322170 is a reply to message #322164]

Thu, 22 May 2008 12:28

Michel Cadot
Messages: 68737
Registered: March 2007
Location: Saint-Maur, France, https...

Senior Member
Account Moderator

dba_tablespaces is part of dictionary (actually catalog) that is in "dict" view.
SYS tables are part of dictionary that are not in "dict" view.

dba_tablespaces.extent_management gives you if the tablespace is LMT or DMT.

Regards
Michel

Report message to a moderator

Re: DMT [message #322175 is a reply to message #322170]

Thu, 22 May 2008 12:43

sdhanuka
Messages: 173
Registered: March 2008

Senior Member

Oh yes clearer..!!! Smile

I hope you understood why was i so confused.

Report message to a moderator

Previous Topic:	Query taking 10 seconds to fetch only 300 records
Next Topic:	Difference in performance of a SQL Query for same execution plan

Goto Forum:

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

]

Current Time: Thu Feb 13 00:56:09 CST 2025