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I wanted to know the difference between oracle Instance and oracle Database,
Difference between a database and an instance [Oracle]
Difference between Service and Instance in Oracle Net Services
Also between ORacle database and relational database.
The Oracle Database (commonly referred to as Oracle RDBMS or simply as Oracle) is an object-relational database management system (ORDBMS)
Put in its simplest explanation it could be summarized as follows:
Hi, I wanted to know the difference between oracle Instance and oracle Database, Also between ORacle database and relational database. Please use simple terminology to explain. Thanks.
1. Database = data files where your data are located
2. Instance = background process and runing programs combined with a shared memory (SGA)
Hope this helps
What is a Database?
We already know that a database is a collection of data. And this data is stored in form of tables at logical level, and in the datafiles at the physical level. There are some other files as well like Redo log files, Control files, Initialization files which stores important information about the database.
What is an Instance?
To view or update data stored in tables/datafiles, Oracle must start a set of background processes, and must allocate some memory to be used during database operation. The background processes and memory allocated by Oracle together make up an Instance.
The Oracle Database (commonly referred to as Oracle RDBMS or simply as Oracle).
A relational database is a database that conforms to relational model theory. The software used in a relational database is called a relational database management system (RDBMS). Colloquial use of the term "relational database" may refer to the RDBMS software, or the relational database itself. A relational database is the predominant choice in storing data, over other models like the hierarchical database model or the network model.
There are two terms that are used with Oracle
Thanks everyone for the prompt reply.Also as said "The background processes and memory allocated by Oracle together make up an Instance." then as database holds database files will it not hold memory?
Database - A collection of physical operating system files
Instance - A set of Oracle processes and a SGA (allocation of memory) .
These two are very closely related but a database can be mounted and opened by allocating set of background process and memory.
Edited by: kcv on Jan 24, 2012 2:41 PM
In the early days (when Oracle came on floppies - for those of you that know what those are) members of some tight-knit groups of DBAs that hadn't seen each other for a while would sometimes greet each other with a joke that went:
1st DBA: How do you startup a database?
2nd DBA: How do you get down off of an elephant?
Both DBAs together: YOU CAN"T
Then they would laugh. Anyone that knew this joke was one of the gang.
The 'how do you startup a database' is a good interview question for a newbie DBA candidate too.
It was a joke because you can't startup a database. You startup an instance. And you can't get down off of an elephant you get down off of a duck.
The "you can't" was a take-off on the 'third base' line of Abbot and Constello's classic old baseball routine.
Oh well, showing my age I guess.
chesplay wrote:Oracle instance
I wanted to know the difference between oracle Instance and oracle Database, Also between ORacle database and relational database.
Please use simple terminology to explain.
The combination of the background processes and memory buffers is called an Oracle instance.
An Oracle database consists of one or more logical storage units called tablespaces, which collectively store all of the database's data.
I will put in slightly different way..I hope you would get understood.
Oracle Instance - As being an computer professional, you might know that RAM is part of your System. Oracle require some RAM in order to work (work like processing the requests - like queries which end users fires/executes), So Oracle gets allocate some RAM with in available memory with in your system. Now, further - as every other program even Oracle product have some programs are used (mandatory) runs as part of instance, in order to server the requests of end users (example - processing your results in order give back results to end -users)
So - It's combination of memory @RAM allocated for Oracle + some programs runs in support = Instance (Oracle Instance).
Oracle Database - As being an computer professional you might search for jobs for better salary or better work as per your needs. So, in order to get an interview calls or further processing at-least at first step the Customer must see through profile - of-course you must have saved or holding a copy in your hard disk. Similary so many business are running all around the world and even they do that their details of their business needs and they do store it similarly, perhaps oracle stores the data in different format which is not read directly but read through sql queries and we can them as data files,as they hold actual data.
I hope you have understood the different between the Oracle Instance and database.
- Thanks & Regards