Re: Updates on Oracle and SQL Server

SQL Server caches all table scans. Oracle caches only index scans (index and data blocks) unless you use the cache option. Together with the newer hardware, this should explain the difference. Also check if you have the same number of indexes on the tables to be maintained.

We have done serveral comparisons between Oracle and SQL Server. Both are good databases. Oracle looses on small scans (caching) and its optimizer is also weak.

Regards,
Urs

"Garrick Bigwood" <garrickb_at_software360.com> wrote in message news:73EY7.42297$Q66.179000_at_NewsReader...
> Hello,
>
> I am doing some comparison testing between SQL Server and Oracle for
> evaluation of possible migration of existing app from SQL server to
Oracle.
> The tests involve doing full table Updates (e.g. Update table1 set col1 =
> 5; - this is basically what our system does!!) on 500,000 rows. Running
this
> on Oracle 8.1.6 on Sun Enterprise 450 server /Solaris 8 (fairly old
> hardware)with files spread across 3 disks , I can get this to run at about
> 40-45 secs; with SQL Server 7 on a Compaq server with Raid 5 (3 disks) and
> 1.1 Gb CPU(server approx 6 months old) this takes about 3 - 4 secs. The
> problem with Oracle seems to be the I/O sub-system and the amount of
> physical writes done to datafiles and rollback files(also redo of course),
> and I'm not sure if when SQL Server completes transaction it has completed
> the writes to disk as Oracle has which makes comparison difficult. I think
> maybe the big difference in times I am seeing is combination of
architecture
> differences(SQL Server would only do two writes to Transaction Logs and
> datafiles) and hardware differences (plus I am not using a Volume manager
on
> the Unix server). Has anyone similar experience of testing SQL Server and
> Oracle, is Oracle slow at Updates, is it the hardware or both or ...??
> thanks.
> Garrick.
>
>
>
>
Received on Fri Jan 04 2002 - 05:49:22 CST