okay, if I hadn't already been convinced not to use it, this would
clinch it... we will have joins of 16+ tables to one of the fact tables
and I can't impede performance. This is a very visible system and needs
to be as good as it can be
- Connor McDonald <hamcdc_at_yahoo.co.uk> wrote:
> You need to benchmark ASSM carefully because it may
> have impact especially on your smaller tables. To
> avoid the concurrency issues, you can end up with
> blocks "sprayed" as rows are created. For example,
> you might add a single row to an (empty) table and end
> up with the table being 10 blocks instead of 1 because
> ASSM tries to spread blocks around in this fashion.
>
> If those tables are targets of joins ( to large
> tables) as they often tend to be in DW, you might be
> trawling through a much larger amount of blocks then
> you need to be...
>
> hth
> connor
>
> --- Rachel Carmichael <wisernet100_at_yahoo.com> wrote:
> > Thanks Ian, that was indeed the question, although
> > the other
> > information is useful as well.
> >
> > if I understand what you are saying correctly, it
> > works but it won't
> > really buy me anything and I might do better
> > controlling the space
> > myself. And while you have had no problems, you've
> > heard negative
> > things about it. I can't afford to have this
> > database not be available
> > so I'll manage them on my own
> >
> > Rachel
> >
> > --- "MacGregor, Ian A." <ian_at_SLAC.Stanford.EDU>
> > wrote:
> > > The question posed was not whether "extent
> > management local" should
> > > be used, but whether automatic segment space
> > management should be
> > > used.
> > >
> > > As this is a data warehouse, I would not expect
> > you to have
> > > transactions trying to change the same block.
> > Assuming you are
> > > loading; that is, inserting data and not doing
> > updates, wouldn't you
> > > try to cram as much data as possible into a block?
> > Seems this could
> > > be done more easily by controlling these
> > parameters yourself
> > >
> > > I've got one system using automatic segment space
> > management without
> > > any problems, however when I posed the same
> > question on using it a
> > > few months ago, the respone which trickled in way
> > highly negative
> > > concerning its usage.
> > >
> > > Ian MacGregor
> > > Stanford Linear Accelerator Center
> > > ian_at_slac.stanford.edu
> > >
> > > -----Original Message-----
> > > Sent: Tuesday, September 03, 2002 8:49 AM
> > > To: Multiple recipients of list ORACLE-L
> > >
> > >
> > > time for me to ask the experts again.
> > >
> > > My data warehouse will be 9.2, with all locally
> > managed tablespaces.
> > > We
> > > will be following what I have taken to calling the
> > "Goldilocks"
> > > principle -- that of small, medium and large
> > tablespace extent sizes,
> > > with variations in that we will separate indexes
> > and data, and will
> > > have even more separation for our fact tables into
> > partitioned tables
> > > and tablespaces.
> > >
> > > However, now comes the time for me to work out
> > storage clauses. And a
> > > quick read through the docs leaves me wondering if
> > I should just turn
> > > on automatic segment-space management and not
> > worry about setting
> > > PCTFREE, PCTUSED and FREELIST parameters. I can't
> > find any real
> > > information or bugs on MetaLink either.
> > >
> > > Does anyone have any experience, good OR bad, with
> > using this
> > > feature?
> > > If you are doing data warehouse work, what are
> > good values for the
> > > parameters if I DO use them? One fact table is
> > likely to be highly
> > > updated (customer info) as we collect more and
> > more specific
> > > information from customers. The rest will be, as
> > you would expect
> > > from
> > > a DW, mostly inserts.
> > >
> > > Help?
> > >
> > > Thanks!
> > >
> > > Rachel
> > >
> > > __________________________________________________
> > > Do You Yahoo!?
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> > > --
> > > Please see the official ORACLE-L FAQ:
> > http://www.orafaq.com
> > > --
> > > Author: Rachel Carmichael
> > > INET: wisernet100_at_yahoo.com
> > >
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> >
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> =====
> Connor McDonald
> http://www.oracledba.co.uk
>
=== message truncated ===
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Author: Rachel Carmichael
INET: wisernet100_at_yahoo.com
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Received on Wed Sep 04 2002 - 08:03:25 CDT