Re: LMT and DMT

"vbaskar" <member24112_at_dbforums.com> wrote in message news:2468993.1044093627_at_dbforums.com...
>
> What is the difference between LMT and DMT ?
>
> Which one is better ?

Depends on your version. Would I touch LMTs in 8.1.5? Nope. Would I touch DMTs in 8.1.7?? Nope.

These days (ie, by the time you get to 9i R2) there's not a lot of choice. LMTS are the default, and if you forget to specify otherwise at database creation time, you get an LMT SYSTEM, and you are forbidden ever afterwards from using DMTs in that database.

Which tells you that Oracle wants you to use LMTs because they are a good thing. They prevent "tablespace fragmentation" (which isn't a performance issue, but is definitely a waste of space issue). They prevent contention for the data dictionary when dozens of segments all decide to extend at the same time. They let you use ASSM, which is (probably) a very good thing in a RAC environment. They mean that we couldn't really give much of a damn about how many extents your segments acquire, because there are precius few performance penalties in going moderately beserk with the number of extents anymore.

And all of that means that the DBA can more or less give up worrying about space management issues in the database.

And although I exaggerate slightly, it's not by much.

LMTs every time, therefore.

Regards
HJR
>
> and in 9i I COULD see everything as LMT only ? Why
>
> Rgds
>
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Received on Sat Feb 01 2003 - 07:22:24 CST