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DMT [message #322073] Thu, 22 May 2008 06:10 Go to next message
sdhanuka
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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
Re: DMT [message #322075 is a reply to message #322073] Thu, 22 May 2008 06:40 Go to previous messageGo to next message
Michel Cadot
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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]

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Re: DMT [message #322079 is a reply to message #322075] Thu, 22 May 2008 06:59 Go to previous messageGo to next message
sdhanuka
Messages: 173
Registered: March 2008
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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
Re: DMT [message #322082 is a reply to message #322079] Thu, 22 May 2008 07:06 Go to previous messageGo to next message
Michel Cadot
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What don't you understand?

Regards
Michel
Re: DMT [message #322108 is a reply to message #322082] Thu, 22 May 2008 09:19 Go to previous messageGo to next message
sdhanuka
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Registered: March 2008
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i mean i am getting really confused.
Re: DMT [message #322111 is a reply to message #322108] Thu, 22 May 2008 09:27 Go to previous messageGo to next message
Michel Cadot
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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
Re: DMT [message #322157 is a reply to message #322111] Thu, 22 May 2008 11:49 Go to previous messageGo to next message
sdhanuka
Messages: 173
Registered: March 2008
Senior Member
Ok..

when we do

select * from dict;

we do not get these dictionary tables.
Re: DMT [message #322158 is a reply to message #322157] Thu, 22 May 2008 11:53 Go to previous messageGo to next message
BlackSwan
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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
Re: DMT [message #322160 is a reply to message #322157] Thu, 22 May 2008 11:58 Go to previous messageGo to next message
Michel Cadot
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"dict" does not show the whole catalog and dictionary, just "top level".

Regards
Michel


Re: DMT [message #322164 is a reply to message #322158] Thu, 22 May 2008 12:06 Go to previous messageGo to next message
sdhanuka
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Registered: March 2008
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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??
Re: DMT [message #322170 is a reply to message #322164] Thu, 22 May 2008 12:28 Go to previous messageGo to next message
Michel Cadot
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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
Re: DMT [message #322175 is a reply to message #322170] Thu, 22 May 2008 12:43 Go to previous message
sdhanuka
Messages: 173
Registered: March 2008
Senior Member
Oh yes clearer..!!! Smile

I hope you understood why was i so confused.

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