Oracle® Database Database Concepts

Oracle? Database

Database Concepts

21c

F31733-04 August 2021

Oracle Database Database Concepts, 21c

F31733-04

Copyright ? 1993, 2021, Oracle and/or its affiliates.

Primary Authors: Lance Ashdown, Donna Keesling, Tom Kyte

Contributors: Drew Adams, Ashish Agrawal, Troy Anthony, Vikas Arora, Jagan Athraya, David Austin, Thomas Baby, Vladimir Barriere, Hermann Baer, Srinagesh Battula, Nigel Bayliss, Tammy Bednar, Virginia Beecher, Bjorn Bolltoft, Ashmita Bose, David Brower, Larry Carpenter, Lakshminaray Chidambaran, Deba Chatterjee, Shasank Chavan, Tim Chien, Gregg Christman, Bernard Clouse, Maria Colgan, Carol Colrain, Nelson Corcoran, Michael Coulter, Jonathan Creighton, Judith D'Addieco, Mark Dilman, Kurt Engeleiter, Bj?rn Engsig, Marcus Fallon, Steve Fogel, Jonathan Giloni, Naveen Gopal, Bill Habeck , Min-Hank Ho, Lijie Heng, Bill Hodak, Yong Hu, Pat Huey, Praveen Kumar Tupati Jaganath, Sanket Jain, Prakash Jashnani, Caroline Johnston, Shantanu Joshi, Jesse Kamp, Vikram Kapoor, Feroz Khan, Jonathan Klein, Andre Kruglikov, Sachin Kulkarni, Surinder Kumar, Paul Lane, Adam Lee, Allison Lee, Jaebock Lee, Sue Lee, Teck Hua Lee, Yunrui Li , Ilya Listvinski, Bryn Llewellyn, Rich Long, Barb Lundhild, Neil Macnaughton, Vineet Marwah, Susan Mavris, Bob McGuirk, Joseph Meeks, Mughees Minhas, Sheila Moore, Valarie Moore, Gopal Mulagund, Charles Murray, Kevin Neel, Sue Pelski, Raymond Pfau, Gregory Pongracz, Vivek Raja, Ashish Ray, Bert Rich, Kathy Rich, Andy Rivenes, Scott Rotondo, Vivian Schupmann, Venkat Senaptai, Shrikanth Shankar, Prashanth Shanthaveerappa, Cathy Shea, Susan Shepard, Kam Shergill, Mike Skarpelos, Sachin Sonawane, James Spiller, Suresh Sridharan, Jim Stenoish, Janet Stern, Rich Strohm, Roy Swonger, Kamal Tbeileh, Juan Tellez, Ravi Thammaiah, Lawrence To, Tomohiro Ueda, Randy Urbano, Badhri Varanasi, Nick Wagner, Steve Wertheimer, Patrick Wheeler, Doug Williams, James Williams, Andrew Witkowski, Daniel Wong, Hailing Yu

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Contents

Preface

Audience Documentation Accessibility Related Documentation Conventions

1 Introduction to Oracle Database

About Relational Databases Database Management System (DBMS) Relational Model Relational Database Management System (RDBMS) Brief History of Oracle Database

Schema Objects Tables Indexes

Data Access Structured Query Language (SQL) PL/SQL and Java

Transaction Management Transactions Data Concurrency Data Consistency

Oracle Database Architecture Database and Instance Multitenant Architecture Sharding Architecture Database Storage Structures Physical Storage Structures Logical Storage Structures Database Instance Structures Oracle Database Processes Instance Memory Structures

xx xx xxi xxi

1-1 1-1 1-2 1-2 1-3 1-4 1-5 1-5 1-6 1-6 1-6 1-7 1-7 1-8 1-8 1-9 1-9 1-9 1-12 1-14 1-14 1-15 1-15 1-15 1-16

iii

Application and Networking Architecture Application Architecture Oracle Net Services Architecture

Oracle Database Documentation Roadmap Oracle Database Documentation: Basic Group Oracle Database Documentation: Intermediate Group Oracle Database Documentation: Advanced Group

Part I Multitenant Architecture

2 CDBs and PDBs

About Containers in a CDB The CDB Root and System Container PDBs

Types of PDBs Purpose of PDBs Proxy PDBs Names for PDBs Database Links Between PDBs

3 Application Containers

About Application Containers Purpose of Application Containers Key Benefits of Application Containers Application Container Use Case: SaaS Application Containers Use Case: Logical Data Warehouse Application Root Application PDBs Application Seed

Application Common Objects About Commonality in a CDB Principles of Commonality Namespaces in a CDB Creation of Application Common Objects Metadata-Linked Application Common Objects Metadata Links Data-Linked Application Common Objects Extended Data-Linked Application Objects

Container Maps

1-16 1-17 1-17 1-18 1-18 1-19 1-19

2-1 2-4 2-5 2-5 2-6 2-7 2-8 2-9

3-1 3-2 3-2 3-2 3-3 3-4 3-5 3-5 3-5 3-6 3-6 3-6 3-7 3-8 3-10 3-10 3-11 3-12

iv

Cross-Container Operations

3-15

Part II Oracle Relational Data Structures

4 Tables and Table Clusters

Introduction to Schema Objects About Common and Local User Accounts Common User Accounts Local User Accounts Common and Local Objects Schema Object Types Schema Object Storage Schema Object Dependencies Sample Schemas

Overview of Tables Columns Virtual Columns Invisible Columns Rows Example: CREATE TABLE and ALTER TABLE Statements Oracle Data Types Character Data Types Numeric Data Types Datetime Data Types Rowid Data Types Format Models and Data Types Integrity Constraints Table Storage Table Organization Row Storage Rowids of Row Pieces Storage of Null Values Table Compression Basic Table Compression and Advanced Row Compression Hybrid Columnar Compression

Overview of Table Clusters Overview of Indexed Clusters Overview of Hash Clusters Hash Cluster Creation Hash Cluster Queries

4-1 4-1 4-3 4-7 4-9 4-9 4-10 4-11 4-13 4-14 4-15 4-15 4-16 4-16 4-16 4-18 4-19 4-21 4-22 4-23 4-24 4-25 4-26 4-26 4-27 4-27 4-28 4-28 4-28 4-29 4-33 4-34 4-36 4-36 4-37

v

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