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Why is it essential to comes back to the foundations?

Updated: Jun 25, 2019

It’s been a while since you’ve taken an Oracle course, and especially the one where you learned about the basics, the fundamentals.


Reading one of my favorites DBA sites, Diana Robete in www.dbaparadise.com she took something essential in one of their articles but I want to complement it.


Maybe some of the basic concepts have been forgotten and, you might need a refresher.

Why is it so important to know the fundamentals? Well, in order to be a good DBA, you must have a good foundation of the Oracle basic components.


As per you know Oracle Database launched not to far away version 18c and 19c flavours and a DBA with a lot of stuff like me sometimes we do not have time to read the new features but sometimes we also forget the fundamentals. I would like to re-cap all of them. Here we go!


Architecture of Database Engine


A database is a collection of data treated as a unit. The purpose of a database is to store and retrieve related information. A database server is the key to information management. In general, a server reliably manages a large amount of data in a multi-user environment so that many users can concurrently access the same data. A database server also prevents unauthorized access and provides efficient solutions for failure recovery.


Client/Server Architecture

An Oracle database system can easily take advantage of distributed processing by using its client/server architecture. In this architecture, the database system has two parts: a front-end or a client, and a back-end or a server.



The Client

The client is a database application that initiates a request for an operation to be performed on the database server. It requests, processes, and presents data managed by the server. The client workstation can be optimized for its job. For example, the client might not need large disk capacity, or it might benefit from graphic capabilities. Often, the client runs on a different computer than the database server. Many clients can simultaneously run against one server.


The Server

The server runs the database software and handles the functions required for concurrent, shared data access. The server receives and processes requests that originate from client applications. The computer that manages the server can be optimized for its duties. For example, the server computer can have large disk capacity and fast processors.


A database instance contains a set of Oracle Database background processes and memory structures. The main memory structures are the System Global Area (SGA) and the Program Global Areas (PGAs). The background processes operate on the stored data (data files) in the database and use the memory structures to do their work. A database instance exists only in memory.


A database instance contains a set of Oracle Database background processes and memory structures. The main memory structures are the System Global Area (SGA) and the Program Global Areas (PGAs). The background processes operate on the stored data (data files) in the database and use the memory structures to do their work. A database instance exists only in memory.


The System Global Area (SGA) is the memory area that contains data and control information for one Oracle Database instance. In other article I will talk further about SGA.


The Program Global Area (PGA) is a non-shared memory region that contains data and control information exclusively for use by server and background processes. I will also talk further in another article.


Background processes are part of the database instance and perform maintenance tasks required to operate the database and to maximize performance for multiple users. Each background process performs a unique task, but works with the other processes. Oracle Database creates background processes automatically when you start a database instance. The background processes that are present depend on the features that are being used in the database. When you start a database instance, mandatory background processes automatically start.



Database system files are used during the operation of an Oracle Database and reside on the database server.

Control files, online redo log files, and archive redo log files can be multiplexed, which mean that two or more identical copies can be automatically maintained in separate locations.

The control file, parameter file, and online redo log files are required for database startup. For more information, see Physical Storage Structures.


Something else that you consider important? Please let me know in the comments box.


Source of Info

https://docs.oracle.com/cd/B28359_01/server.111/b28318/intro.htm#CNCPT915

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