Re: Locally Managed Tablespaces - any cons???

"Frank Hubeny" <fhubeny_at_ntsource.com> wrote in message news:3B7CADF3.432D3FF6_at_ntsource.com...
> I tend to avoid locally managed tablespaces for the following reasons:
>
> (1) A bug using the locally managed tablespaces and read only tablespaces
in
> 8i almost prohibits using these two features together at least in 8.1.6
(see
> Note 131886.1 on MetaLink for more info).
>
> (2) Once the storage parameters of the locally managed tablespace are set,
> they cannot be changed without rebuilding the tablespace. Setting the
> default storage parameters of a dictionary managed tablespace is far more
> flexible.

Why on earth would you ever *want* to change a tablespace's default storage parameters? Doing so affects nothing already created within the tablespace (they've already picked up the old default as their own, operative, storage clause).

LMT's inability to do something that has no point in any event is hardly a drawback.

But, assuming you had a desperate need to re-jig the thing, 8i's 'move tablespace' makes creating a new tablespace with the "correct" size and then porting all segments into it a doddle.

The business about DBA_SEGMENTS running slowly is true.

Regards
HJR
>
> (3) Performance of queries against dba_segments appear, at least to me, to
> be far slower than similar queries against dictionary managed tablespaces.
>
> Locally managed tablespaces may have a performance benefit, as others have
> mentioned, if there are many concurrent changes to the extents in the
> tablespace. I would be curious to know how volatile a tablespace has to
be
> to justify making it locally managed rather than dictionary managed.
>
> However, since there are costs, in at least flexibility, with using
locally
> managed tablespaces, using them indiscriminately does not appear to be
> prudent.
>
> Frank Hubeny
>
>
>
>
> Ron Gardiner wrote:
>
> > New for 8i (I believe) is locally managed tablespaces...
> >
> > From what I've read, sounds like there is no reason NOT to use them. Can
> > they be used for all types of TS?... rollback segs, temporary, how about
> > system itself?
> >
> > Any feedback would be appreciated!
>
Received on Fri Aug 17 2001 - 17:55:38 CDT