Re: Relational Model and Search Engines?

Leandro Guimarães Faria Corsetti Dutra wrote:

> Em Mon, 03 May 2004 20:42:33 +0000, Alfredo Novoa escreveu:
>
>

>>>	My understanding is that they in fact were a big, ugly cache.
>>
>>Main memory DMBS only means that the data reside in memory and not in
>>disks. It is possible to make ugly and beauty MMDBMSs.

In-memory access does not have to go across any bus to any device. When you are dealing with 8,000 TPS this does have an effect.

>
> More specifically, how is it that it can have data in memory
> and still COMMIT?

Commits are done to the disk, as usual (to the journal file). Depending on the application, these may be either synchronous (right now), or deferred until the next millisecond or the next 10 commits or something like that. If you can live with losing the last 10 transactions in case of a crash, you can live with an in-memory database. (It's a tradeoff.)

>
> Even more specifically, is it possible to do it decently with
> a relational language or SQL?
>
>

Yes.

-- 
"It is impossible to make anything foolproof
because fools are so ingenious"
  - A. Bloch