RE: Convert to Locally-Managed Tablespaces

Jared - I don't know SAP, but other canned applications have a "wonderful" process they put you through every few years called an upgrade. Often you end up creating another database and moving the data. This is a great opportunity for the DBA to fix some issues like this. However, since SAP is used by some REALLY large organizations with really, really large amounts of data, perhaps SAP uses a different practice. I would like to know if that is the case.

Dennis Williams
DBA
Lifetouch, Inc.
dwilliams_at_lifetouch.com

-----Original Message-----
Sent: Monday, January 05, 2004 8:09 PM
To: Multiple recipients of list ORACLE-L

Tanel,

That's a good idea. I briefly considered this, but didn't really dig into it.

The systems I need to do this on is our SAP systems, and downtime is a precious commodity, especially for production.

I just may try this on our test system. The problem with SAP of course, and many other ERP's is that there are 22k+ tables, which could consume a bit of time.

The amount of fragmented space that would be recovered is probably not worth the trouble of this procedure, depending on how much time it takes.

I see that you too need to keep the original tablespace names, is this SAP per chance?

If you have already performed a test of this, what kind of times are you seeing, along with relevant platform information, and the number of tables/indexes?

Jared

On Mon, 2004-01-05 at 16:49, Tanel Poder wrote:
> Hi!
>
> > This is what I will need to use on our systems, as there are about 400
gig
> > of data and indexes. 200 gig of data is too large to export/import, at
> least
> > it is for this project. So dbms_space_admin it will be.
>
> I'm about to do a reorg+conversion of a 250GB 8.1.6 database in next week,
> here's what I'll do (there is practically no free space for temporary
> usage):
>
> 1) Export index definitions (normal export with rows=n)
> 2) Drop all indexes
> 3) use alter table move with parallel 16 and nologging to move all tables
to
> old index tablespaces (the indexes consumed more space than tables)
> 4) drop and recreate data tablespaces
> 5) use alter table move again to move tables back (the segments have to
> reside in original tablespaces, otherwise I could have skipped this step)
> 6) drop and recreate index tablespaces
> 7) get index definitions out of exportfile and modify them to add parallel
&
> nologging (with big sort area size)
> 8) rebuild indexes
> 9) do a full backup
>
> It might help to recreate index tablespaces even before step 3, to speed
up
> parallel table moving a bit..
>
> Maybe you want to test this Jared, this approach is much faster than
> export/import, because everything can be done with direct path operations
> and nologging (import doesn't have direct path facility, so regular array
> inserts are used, which always require logging as well).
> Also, your tables/datablocks will be optimized after moving them (which is
> not the case with dbms_space_admin) and you don't have to have any space
for
> reorg in case your cleared index tablespace can temporarily accommodate
your
> data.
>
> > IIRC one of the drawbacks of using dbms_space_admin to convert is
> > that you won't be converting to nice uniform extent sizes for existing
> data.
>
> Yes, and if your tablespace is fragmented, the fragmentation will remain
> there, despite your conversions (of course, smaller extents might be able
to
> use some of this fragmented space later on).
>
> Tanel.
>
>
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> --
> Author: Tanel Poder
> INET: tanel.poder.003_at_mail.ee
>
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Author: Jared Still
  INET: jkstill_at_cybcon.com

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Author: DENNIS WILLIAMS
  INET: DWILLIAMS_at_LIFETOUCH.COM

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