Oracle® Database Database Concepts

1 oracle DatabaseDatabase Concepts19cE96138-06 April 2021 oracle Database Database Concepts , 19cE96138-06 Copyright 1993, 2021, oracle and/or its Authors: Lance Ashdown, Donna Keesling, Tom Kyte, Joe McCormackContributors: Drew Adams, Ashish Agrawal, Troy Anthony, Vikas Arora, Jagan Athraya, David Austin,Thomas Baby, Vladimir Barriere, Hermann Baer, Srinagesh Battula, Nigel Bayliss, Tammy Bednar, VirginiaBeecher, Bjorn Bolltoft, Ashmita Bose, David Brower, Larry Carpenter, Lakshminaray Chidambaran, DebaChatterjee, 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, LijieHeng, Bill Hodak, Yong Hu, Pat Huey, Praveen Kumar Tupati Jaganath, Sanket Jain, Prakash Jashnani.

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7 oracle Corporation and its affiliates will notbe responsible for any loss, costs, or damages incurred due to your access to or use of third-party content,products, or services, except as set forth in an applicable agreement between you and PrefaceAudiencexxiDocumentation AccessibilityxxiRelated DocumentationxxiiConventionsxxii Changes in This Release for oracle Database ConceptsChanges in oracle Database Release 19c, Version in oracle Database Release 18c, Version Introduction to oracle DatabaseAbout Relational Databases1-1 Database Management System (DBMS)1-1 Relational Model1-2 Relational Database Management System (RDBMS)1-2 Brief History of oracle Database1-3 Schema Objects1-4 Tables1-5 Indexes1-5 Data Access1-6 Structured Query Language (SQL)

8 1-6PL/SQL and Java1-6 Transaction Management1-7 Transactions1-7 Data Concurrency1-8 Data Consistency1-8 oracle Database Architecture1-9 Database and Instance1-9 Multitenant Architecture1-11 Sharding Architecture1-14 Database Storage Structures1-16iiiPhysical Storage Structures1-16 Logical Storage Structures1-17 Database Instance Structures1-18 oracle Database Processes1-18 Instance Memory Structures 1-18 Application and Networking Architecture1-19 Application Architecture1-19 oracle Net Services Architecture1-20 oracle Database Documentation Roadmap1-21 oracle Database Documentation: Basic Group1-21 oracle Database Documentation: Intermediate Group1-22 oracle Database Documentation: Advanced Group1-22 Part I oracle Relational Data Structures2 Tables and Table ClustersIntroduction to Schema Objects2-1 Schema Object Types2-2 Schema Object Storage2-4 Schema Object Dependencies2-5 SYS and SYSTEM Schemas2-7 Sample Schemas2-8 Overview of Tables2-9 Columns2-10 Virtual Columns2-10 Invisible Columns2-10 Rows2-11 Example.

9 CREATE TABLE and ALTER TABLE Statements2-11 oracle Data Types2-13 Character Data Types2-14 Numeric Data Types2-16 Datetime Data Types2-17 Rowid Data Types2-18 Format Models and Data Types2-19 Integrity Constraints2-20 Table Storage2-21 Table Organization2-21 Row Storage2-22 Rowids of Row Pieces2-22 Storage of Null Values2-23ivTable Compression2-23 Basic Table Compression and Advanced Row Compression2-23 Hybrid Columnar Compression2-24 Overview of Table Clusters2-28 Overview of Indexed Clusters2-29 Overview of Hash Clusters2-31 Hash Cluster Creation2-31 Hash Cluster Queries2-32 Hash Cluster Variations2-33 Hash Cluster Storage2-34 Overview of Attribute-Clustered Tables2-35 Advantages of Attribute-Clustered Tables2-36 Join Attribute Clustered Tables2-37I/O Reduction Using Zones2-37 Zone Maps2-37 Purpose of Zones2-38 How a Zone Map Works.

10 Example2-38 Attribute-Clustered Tables with Linear Ordering2-39 Attribute-Clustered Tables with Interleaved Ordering2-40 Overview of Temporary Tables2-42 Purpose of Temporary Tables2-43 Segment Allocation in Temporary Tables2-43 Temporary Table Creation2-43 Overview of External Tables2-44 Purpose of External Tables2-44 Data in Object Stores2-45 External Table Access Drivers2-45 External Table Creation2-46 Overview of Blockchain Tables2-47 Row Chains2-47 Row Content2-48 User Interface for Blockchain Tables2-49 Overview of Immutable Tables2-49 Overview of Object Tables2-503 Indexes and Index-Organized TablesIntroduction to Indexes3-1 Advantages and Disadvantages of Indexes3-2 Index Usability and Visibility3-3 Keys and Columns3-3vComposite Indexes3-4 Unique and Nonunique Indexes3-5 Types of Indexes3-6 How the Database Maintains Indexes3-7 Index Storage3-7 Overview of B-Tree Indexes3-8 Branch Blocks and Leaf Blocks3-9 Index Scans3-10 Full Index Scan3-10 Fast Full Index Scan3-11 Index Range Scan3-12 Index Unique Scan3-12 Index Skip Scan3-13 Index Clustering Factor3-14 Reverse Key Indexes3-16 Ascending and Descending Indexes3-17 Index Compression3-17 Prefix Compression3-18 Advanced Index Compression3-20 Overview of Bitmap Indexes3-21 Example.