Re: In-memory Database

In article <u1dqks0spr7rsco0k4bjlteom1o7dr9n82_at_4ax.com>,   Alik <omelnikov_at_hotmail.com> wrote:
> I'm new to Oracle.
> I have a relatively small database (~100MB) and 1GB
> of memory on the server. What I want to to to speed up
> little bit is to put the database into memory.
> So all reads will be from memory and all writes - to
> the disk with memeory also updated.
> How can I do this? How to place whole database into the
> memory.

Well, part of the reason Oracle is architected the way it is is for reliability - you want to be able to be certain that what you write is what you get, even if the computer crashes. So, even though you can make memory look like disk, you may not want to.

Aside from that, Oracle is quite complicated internally, and actually does a lot of stuff in memory. It uses its System Global Area as a buffer for both code and data, so you may lock code in memory, and the mere act of using data puts it in memory (and whether it stays there follows certain rules). Data is also updated in memory, then written to disk at leisure, so to speak. Also, some modern hardware makes disks look almost as fast as memory (I've just got a new SANS and am utterly amazed).

So before you bother working against the wheel, read the System Concepts manual and tune your database. When you test performance, be sure to test it under load - if you just test how long it takes for the data to be buffered, you are cheating yourself. Also, most performance gains happen through proper coding and indexing.

jg

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