understanding oracle terminology - instance, database, sid, schema

From: The Quiet Center <thequietcenter_at_gmail.com>
Date: Thu, 24 Jun 2010 08:24:08 -0700 (PDT)
Message-ID: <2ed3363f-074f-4152-914b-910bb87f66d5_at_w12g2000yqj.googlegroups.com>

hi, I'm an open source developer who has been cast into the wide wide world of Oracle. As a former MySQL user mainly (no boos please :), there is a lot of Oracle terminology that I dont understand.

Specifically:
- instance

• database (it appears that a single host and port can have several databases)
• sid
• schema (it appears that a single database can have several schemas and that a schema is a collection of tables, views, triggers, etc)
• user (it appears that a user can have access to various schemas and various permissions within schemas... contrast with MySQL where there are only databases)

Beyond definitions for the above, my goal is to ask: how do you uniquely identify a schema? We are running both 10g and 11g here and so we cannot truly refer to a schema by the name alone without qualifying it with the database. But since the word "instance" is being thrown around here as well, I have to wonder what is meant by that also.

Thanks,
Terrence Received on Thu Jun 24 2010 - 10:24:08 CDT