"Howard J. Rogers" <howardjr_at_www.com> wrote in message
news:3be0fd1c$0$9820$afc38c87_at_news.optusnet.com.au...
> I have to say that Steve's answer where he says "I would have a preference
> for dictionary management for any tablespace with a large number of mostly
> small constant sized segments" rather begs the question -how do you ensure
> that the segments *are* 'constantly sized'? Well, using locally managed
> tablespace is the only solution that actually guarantees that!
My reading of Steves answer was that he had a preference for dictionary
management where the segments were lookup tables and their ilk. i.e they
don't grow *by design*. This of course means , as so often, one has to
actually understand the data you are looking after. In this situation I can
go along with the recommendation - though whether I'd actually be bothered
in practice is a moot point. LMT's are great because they avoid
fragmentation caused by different sized extents. If your table isn't growing
it won't fragment. In addition I suspect that most such tables should be
allocated to a keep buffer pool anyway so physical io wouldn't be a big
issue. However having said all that Steve then gives SYSTEM as an example of
such a tablespace and it doesn't fit my reading of the above at all. Of
course the best reason of all for making SYSTEM dictionary managed is that
you have to!
--
Niall Litchfield
Oracle DBA
Audit Commission Uk
Received on Thu Nov 01 2001 - 03:40:38 CST
