Re: Re-organising a database?

tim.kearsley_at_milton-keynes.gov.uk (Tim Kearsley) wrote in message news:<725736ef.0304140119.6623ab37_at_posting.google.com>...
> Hi all,
>
> Environment is:
>
> Oracle 8.1.7 on AIX 4.3.3 on RS6000 SP hardware
>
> I've got a legacy database, about 30 Gbytes in size, which I would
> very much like to re-organise. Primarily I would like to implement
> LMTs and to put the datafiles into a structure which is fairly close
> to OFA.
>
> The obvious solution I suppose is to create the new database and
> export/import from the existing one. My problem is the time this
> appears to be taking. A trial took some two days by the time I had
> imported, re-created indices and solved a few problems with invalid
> packages. The database is pretty heavily used and it is going to be
> hard for me to sell a weekend's downtime to the users.
>
> Are there any other techniques I could use to reduce this downtime? I
> admit that I haven't tried tuning the export/import process. At
> present the export is done to a Unix pipe which compresses the dump
> file on the fly. Likewise the trial import was done by uncompressing
> the dump file on the fly. Is it likely to be substantially faster to
> export to multiple files rather than compressing (I am facing an OS
> filesize limit)?
>
> Any thoughts or ideas very welcome.
>
> Thank you.
>
> Tim Kearsley
> Database Manager
> Milton Keynes Council

Tim, here is a consideration. If space is available add a new tablespace and migrate the existing objects tablespace by tablespace. This could require more windows but the windows could be shorter.

Also you might be able to take advantage of the online feature of index rebuilds and migrate your indexes one by one during the day. When you move the table the indexes would have to be rebuilt again, but the tablespace allocation process time would be out of the way.

If you have any history tables and job worktables you might be able to grab them and move those during normal operations so the work is out of the way before your maintenance window thereby reducing the work that has to be done in the window.

HTH -- Mark D Powell -- Received on Mon Apr 14 2003 - 10:39:01 CDT