Re: One sever one database or one server many databases is better ?

On Tue, 29 Sep 1998 14:38:25 +0800, "Andrew" <andrewc_at_psc.com.tw> wrote:

>There are three reporting systems independently in one database, but its
>buffer cache hit ratio is low (60%).
>Could you give me a suggestion that I shoud divide into 3 databases ?
>
>

Not sure if you mean on the same machine? However, if the database is purley for reporting purposes and you are reporting mainly from large tables (> 5 blocks), then Oracle will not cache the data, and you will get a poor CHR. This is because tables > 5 blocks are read using multiblock reads. Such blocks are placed at the least recently used end of the buffer cache, so they quicky age out. This prevents blocks which are frequently being revisited from being flushed out by batch applications/reports. The CHR will typically rise for transaction processing systems.

If your system is running slowly, consider other options such as HASH_JOINS, PARRALEL query slaves etc. You should also ensure that the SQL is well written.

In any case if you did mean on the same machine, you would simply be putting extra load on the machine (three times the number of Oracle background processes and 3 SGAs, you may as well increase the buffer cache of the existing database. Received on Wed Sep 30 1998 - 18:38:32 CDT