Re: database concept - Sybase vs. Oracle

From: Hans Forbrich <forbrich_at_tibalt.supernet.ab.ca>
Date: 1996/10/27
Message-ID: <32741C50.2715_at_tibalt.supernet.ab.ca>#1/1

Look at it this way:

	database requires structure & physical space
	instance requires memory & CPU cycles

	a special database, whose schema is owned by SYS
	is required for each Oracle instance.

	additional databases may be defined under additional
	schemas to provide data pertainent to local requirements.

	An instance without a database is what exists between
	the time of startup & initial creation (before sql.bsq)

	A database without an instance is what exists
	between the successful completion of the shutdown
	command and the successful completion of the next
	startup command.

Part 1: Database (schema)

---

From my experience, an Oracle database is usually reduced to 1 schema, although it can be convenient to have a 'database' associated with several different apps run from several schemas.

A practical example:

    Billing system & customer information system

Both use overlapping data. Customer information, if handled by a separate org., would be best kept in a separate schema (database) from the billing schema.

Conversely, a schema may hold more than 1 database. Another practical example:

        Billing database & customer information database

if handled by the same department, it might be better to put these somewhat disparate sets of information under 1 schema.

Part 2: INstance

---

An instance is the set of processes (CPU cycles & memory) required to provide access & control of the databases.

Normally, I recommend 1 instance per CPU or machine.

Normally, I recommend the database & schema be duplicated on a separate instance for testing or training or non-production development.

Normally, the client only has 1 machine they want to place Oracle server on.

Therefore, I suggest, place both instances on the same machine and, when performance is a factor, shut down the test instance.

Hope this ain't to confusing ... it makes sense to me :-)

/Hans

Gordon E. Hooker wrote:
>
> lesliet_at_u.washington.edu (L. Tseng) wrote:
>
> Leslie,
> I can't speak for the others out there, but unless there is a really good reason
> to do so we don't use multiple instances, we use different schemas.
>
> Gordon
> >
> >I am interested in gathering info on how Oracle DBAs handle
> >database vs Sybase DBAs.
> >
> >In Sybase, creating a database is an easy task and all databases share the
> >same memory space. In Oracle, the schema seems more like the "database"
> >concept in Sybase. I wonder if Oracle DBAs actually create database
> >or instance all the time to deal different applications.
> >
> >-Leslie
> >
Received on Sun Oct 27 1996 - 00:00:00 CEST