Re: Large Oracle databases?

In article <2pp8pr$255_at_access1.speedway.net>, lknutsen_at_speedway.net (Leif Knutsen) wrote:

>
> We are investigating the possibility of implementing a large database on
> Oracle 6 (to be migrated to 7 at some point - we hope :)
>
> Does anyone have experience implementing databases with row sizes of 5
> million or more? I'd like to know hardware and software specifics, as
> well as implementation and skill requirements.
>
> This would be incredibly helpful. Please post here or send me e-mail, as
> you feel is appropriate.
>
> Thanks in advance.
>
> Leif Knutsen

Hi Leif,

We are running a Oracle 7.0.12 database with one table with 20 mio records. The table occupies ca 3 gig and the index about 2 gig. I would strongly recommend to use the v7 because migrating is difficult and time intensive.
Be aware of following problems if you do an export.

An export should be no problem; remember to first to compress the extents or not.
If you do an import, your rollback segments have to be large enough or use autocommit
(every 100000 records or so).
You might have to create the table and index first because creating an index on an existing
large table might need very much free tablespace. Remeber to plan your segmenting carefully. With, for example blocksize 4096 (standard)
maxextents is about 250.
An import into an unindexed table is much faster on the other hand. The insert performance is constatnt, regardless of the size of the table. Be sure to access data using an indexed key. If you do somthing like 'select * from mytable where name = 'MILLER' 'without an index
might take easily longer than one hour.

I hope this helps,

Toni Received on Wed May 04 1994 - 23:43:02 CEST