Questions and Answers
What is described by the relationship that allows the value of one attribute to be used to find the value of another attribute?
Which term refers to an attribute that can find the value of another attribute?
What is the term for a key that uniquely identifies a value in a table?
Which of the following defines and manages database structures?
Signup and view all the answers
What class of SQL commands is used to manipulate data in a database?
Signup and view all the answers
What is the purpose of a DCL command?
Signup and view all the answers
What kind of view is created and stored on the database and updates with underlying data changes?
Signup and view all the answers
What type of view is computed when accessed and not stored in memory?
Signup and view all the answers
What is defined as data about the data in a relational database?
Signup and view all the answers
Which term refers to the ordered collection of elements in a database context?
Signup and view all the answers
What process updates data on multiple nodes of a distributed database?
Signup and view all the answers
What term describes a database that remains consistent across nodes even during failures?
Signup and view all the answers
What is the term for eliminating redundancy by breaking relations into two or more tables?
Signup and view all the answers
What defines the schema in a database?
Signup and view all the answers
What is used to remove unwanted database objects permanently?
Signup and view all the answers
What describes the intersection of two data sets?
Signup and view all the answers
What describes a database that can be accessed in main memory for higher performance?
Signup and view all the answers
What does the CAP Theorem state?
Signup and view all the answers
Study Notes
Database Concepts
- Functional Dependency: Relationship where one attribute's value determines another attribute's value within a relation.
- Determinant: An attribute used to uniquely identify another attribute's value.
- Candidate Key: Attributes that can uniquely identify every other non-key attribute in a table; must be unique and minimal.
- DDL (Data Definition Language): Defines and manages database structures; includes commands like CREATE, DROP, ALTER, TRUNCATE, and RENAME.
- DML (Data Manipulation Language): Responsible for adding, deleting, and modifying data stored in a database.
Database Security
- DCL (Data Control Language): Manages user accounts, permissions, and access within a database.
Views in Databases
- Materialized View: A physical view that stores data and updates when the underlying data changes; uses memory space.
- Virtual View: Not stored in memory; calculated and displayed only when accessed.
Data Handling and Structures
- Metadata: Data that describes other data, such as columns, names, and data types.
- Tuple: An ordered collection of elements in a database context.
Querying and Performance
- Hit Ratio: Percentage of table rows selected by a query.
- Table Scan: Directly reads data blocks without using an index.
- Index Scan: Reads index blocks sequentially to locate needed table blocks.
- Binary Search: Efficient index search method that repeatedly divides the index in half until a match is found.
Database Architecture
- Tablespace: Maps one or more tables to a single file within a database.
- Logical Design: Specifies database elements like tables, columns, and keys; often referred to as schema.
- Physical Design: Focuses on how tables are organized on the storage media.
Core Database Components
- Query Processor: Interprets and compiles queries into instructions for the storage engine, returning results to applications.
- Connection Manager: Manages communication between database tools and the query parser.
Data Management
- Storage Engine: Translates query instructions into file system commands for data retrieval or modification.
- File System: Organizes data on storage media, containing user data, log files, and data dictionaries.
Cache and Buffer Management
- Cache Manager: Stores reusable information in main memory for quick access.
- Buffer Manager: Maintains data blocks in memory for possible reuse.
Database Design
- Normalization: Process of organizing data to eliminate redundancy by breaking relations into well-formed tables.
- Denormalization: Combines tables into a single table to enhance query performance at the cost of redundancy.
Data Types and Transactions
- Operational Data: Real-time data utilized for daily business operations; focused on current information.
- Analytic Data: Summarized data used for decision-making, typically updated at fixed intervals.
Advanced Concepts
- Distributed Transactions: Updates that require commitment on multiple nodes, ensuring all nodes succeed or none do.
- CAP Theorem: States that a distributed database system cannot simultaneously ensure consistency, availability, and partition tolerance.
Relationship Management
- Weak Entity: An entity that depends on another entity for its existence.
- Strong Entity: An entity that can exist independently within the database.
Joins and Indexes
- Inner Join: Returns only matching values between two tables.
- Left/Right Outer Join: Retrieves unmatched data from one table while including matched records from the other.
- Primary and Secondary Index: Index types that organize data for faster query times; primary is based on sort column, while secondary is not.
Partitioning Strategies
- Horizontal Partition: Subset of rows within a table.
- Vertical Partition: Subset of columns within a table.
- Hash Partition: Computes partitioning based on a defined hash function applied to row data.
Miscellaneous
- Function Index: Index based on a function applied to index column values for efficient querying.
- Bitmap Index: Uses a grid of bits to represent existence of values, often for low-cardinality columns.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Test your knowledge on key concepts in relational databases with these flashcards. Focus on functional dependencies, determinants, and unique attributes for mastering database principles. Ideal for WGU D426 students preparing for assessments.
