1 Oracle Database 12c Fundamentals Slides

Oracle Database 12c Fundamentals Exploring the Oracle Database 12c Architecture: Part 1 Timothy Warner timwarnertech.com @TechTrainerTim

Overview: Exploring the Oracle Database 12c Architecture Part 1/1  Goals of this course and learning path  What is Oracle Database 12c?  Understanding Oracle client/server architecture  Understanding Oracle Database 12c memory structures

Goals of this Course and Learning Path  Students come from a variety of backgrounds:   

New to databases New to Oracle (previous experience with other platforms) New to Oracle Database 12c

 Oracle Certified Associate (OCA) learning path: 

Oracle Database 12c Fundamentals

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Oracle Database 12c Installation and Upgrade

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Oracle Database 12c Disaster Recovery and Data Movement

 Get familiar with Oracle University (education.oracle.com)

What is Oracle Database 12c?  A database is an organized collection of data that is treated as a unit  A relational database management system (RDBMS) is the infrastructure that supports multi-user database access 

Secure data storage, quick retrieval by using SQL

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Oracle is called an object-relational database

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EF “Ted” Codd (1923-2003)

 Key terms in relational theory: 

Relation = table

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Attribute = column

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Tuple = row

A Bit of Oracle Version History  Oracle v1 written but never officially released in 1978  Oracle 8i released in 1999 (i = Internet)  Oracle 10g released in 2003 (g = grid computing)  Oracle 12c released in 2014 (c = cloud)

Understanding Oracle Client/Server Architecture  Client (not the user): application that communicates either through a middle-tier (middleware) application or directly with Oracle server  Middle tier: Homegrown LOB, Oracle Fusion Applications/Middleware 

HTTP(S) Web server

 Oracle Database itself comprises the “back end” storage tier 

Although the platform is capable of declarative/procedural logic

 Oracle Exadata Database Machine

Database and Instance  Instance: Shared memory area (system global area, or SGA) and background processes  Database: Set of files, located on disk, that store data 

Data files, ORL files, control files, etc.

 Single instance vs. clustered (grid) instance: 

Cluster involves several instances that access shared storage and a single database in an active/active configuration

 Multitenant Architecture (New in 12c!) 

Container database (CDB) with multiple pluggable databases (PDBs)

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Provides hardware cost reduction, easier management/monitoring

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Updates and maintenance can be performed just once on the CDB

Oracle Database 12c Memory Structures  System Global Area (SGA): Group of shared memory structures that store data and manage information for a single database instance  Program Global Area (PGA): Stores data and manages information for a server process or background process

System Global Area (SGA) Components  Database buffer cache: Stores copies of data blocks read from data files and waiting to be written to data files  Redo log buffer: Circular buffer that stores all changes made to the DB (can reconstruct DDL or DML operations)  Shared pool: “Catch all” bucket: Shared SQL, Data Dictionary cache, etc.  Large pool: Stores memory allocations that are larger than the shared pool can handle (overflow)  Java pool: Stores session-specific Java code within the JVM  Streams pool: Used in Oracle Streams database replication  Fixed SGA: Internal housekeeping area (locks, processes, etc.)

Program Global Area (PGA) Components  File clerk/countertop analogy for understanding the server process and the PGA  Session memory: logon information and session-related data  Private SQL area: Query execution work data  Restricting the PGA size (new in 12c!) 

PGA_AGGREGATE_LIMIT initialization parameter

Managing Memory in Oracle Database 12c  Automatic Memory Management 

MEMORY_TARGET initialization parameter

 Automatic or Manual Shared Memory Management 

Pertains to the SGA

 Automatic or Manual PGA Memory Management

Summary  Oracle Database is the back-end storage tier in a typical multi-tier client/server application architecture  An Oracle “database” actually consists of two parts: the instance and the database files  An Oracle instance consists of several memory structures and background processes 

SGA

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PGA

 The Oracle database, proper, consists of the file system objects 

Logical vs. physical distinction is a big deal with Oracle products