Re: SGA sizing for high-performance OLTP database

Hi Jonathan,

    Although the purists will complain because they are convinced that cache should only be used for small tables and indexes....

    If I were you I would stuff the indexes into cache. If you can keep the indexes for your two high volume tables in cache you will be able to retrieve data with something less than one disk access per retrieval (remember the Least Recently Used data is still in RAM so it may not require a disk access to retrieve recently accessed data).

Regards
Jerry Gitomer

Jonathan Robinson wrote in message
<7q5q8h$7f3_at_romeo.logica.co.uk>...
>The OLTP system I'm working on requires extremely fast data
retrieval -
>reads and writes, no updates. The platform is Solaris 2.6 with
Oracle 8.1.5.
>In order to meet clients performance requirements I have been
looking at
>ways of optimising the database eg. keeping an important index
on our most
>significant table in cache, keeping the last 15 minutes of data
in cache
>etc. I understand the max. SGA size available on this
architecture would be
>3.75Gb so I am going to be limited in what I can keep in
physical memory and
>what will be swapped out. The 2 most significant tables (where
90% of
>transactions go through) are 40Gb and 70Gb in size. Any pointers
as to where
>I can gain performance uplift ?
>
>System hasn't been implemented yet so anybody with information
based on past
>experiences of implementing systems with similar
high-performance
>requirements would be much appreciated.
>
>Cheers.
>
>
>
>
>
Received on Fri Aug 27 1999 - 07:49:24 CDT