Re: Oracle vs SQl Server

I might only comment that redo has absolutely zilch to do with "provid[ing] the mechanism for allowing all readers to continue reading data"... that is ROLLBACK, not redo.

I might also add that Oracle doesn't "try to grab" anything: the size of each Oracle Instance is entirely determined by the settings which you, the DBA, make in the respective init.oras.

I might finally add that the presence of free space within a tablespace has absolutely zero effect on performance -unless it is a lot of little bits of free space. In which case, we can confidently state that you have allowed fragmentation to occur, and it is the *fragmentation* which is the issue, not the amount of free space.

Apart from all that, you aren't a million miles wrong.

Regards
HJR
> even when someone is writing to the same area
"Mike Krolewski" <mkrolewski_at_rii.com> wrote in message news:92mtnj$r6v$1_at_nnrp1.deja.com...
> In article <3A4EE07F.F4609514_at_someone.edu>,
> Some Body <somebody_at_someone.edu> wrote:
> > I have a basic question with regards this comparison:
> >
> > What are the relative disk-space requirements for the program files
 and
> > the data? I'm guessing that Oracle needs at least twice the disk
 space
> > for the data, because of the need to hold the redo logs, archive logs
> > and also the need to preallocate space not yet needed for data. SQL
> > Server, I believe, gets more disk space as needed from the OS. Is
 this
> > correct?
> >
>
> Not completely.
>
> The redo logs, archive logs do take up more space. The archive can be
> shut off. The redo logs are part of the main feature of Oracle. They
> provide the mechanism for allowing all readers to continue reading data
> even when someone is writing to the same area. It is possible to
> restrict this area, but at some cost. When running on a bigger system
> -- the idea of using 200M - 1G of space for redo logs is not terribly
> significant. There are also other areas like SYSTEM, TOOLS, TEMP and
> USER -- default tablespaces used for a variety of purposes.
>
> Similarly Oracle trys to grab some of the memory. I have two instances
> each using about 1.8G of RAM. Not a lot relative the overall available
> space -- 12G in this case.
>
> As to the size of data storage, it is possible to either preallocate or
> allow the system to expand as is needed. Generally one want to have
> within 20% of the actual data. Oracle will slow down ( Had this happen
> to me when the initial load was 10% of the space ) if too much free
> space is present in any give tablespace. Tablespaces are designed by
> the user to grow at a specific rate. The amount is generally a lot
> bigger than the next row. Within the tablespace -- data is allocated
> via extents, a subdivision of the tablespace.
>
> As to using twice the space, it has alot to do with the amount of data.
> When one is working with 2-5Tbytes of data, the system areas (redo,
> system, etc) are not really significant. I just finished setting up a
> database -- I would estimate that the system is using 2-3G when all the
> tablespaces are expanded to their limits.
>
> If you are trying to get Oracle to run on a small machine -- it can be
> done. I had a system that ran in 3G, 500M for the system, 2.5G for data.
>
> As to a comparison, I am not sure what the issue is. Without redo logs,
> you are really in a quandry. Dynamically allocating all disk usage at
> runtime is expensive. Even on laptops, the idea of having 30-60G is not
> unexpected. Storage volume is generally not a concern of most
> developers.
>
>
> --
> Michael Krolewski
> Rosetta Inpharmatics
> mkrolewski_at_rii.com
> Usual disclaimers
>
>
> Sent via Deja.com
> http://www.deja.com/
Received on Sun Dec 31 2000 - 04:38:54 CST