DBMS ARCHITECTURE Flashcards
(28 cards)
What are the typical DBMS Component Modules?
DBMS languages, DBMS Interfaces, DDL Compiler, Privileged Commands, Query Compiler, Query Optimizer, Precompiler, DML Compiler, Host Language Compiler, Compiled Transaction, Runtime Database Processor, Stored Data Manager
DBMS languages include Data Definition Language (DDL), Data Manipulation Language (DML), and Data Control Language (DCL).
What is Data Definition Language (DDL)?
Used by the DBA and database designers to specify the description of the database.
Example: CREATE TABLE student( name VARCHAR2(50), student_no NUMBER(9), classification VARCHAR2(9) );
What is Data Manipulation Language (DML)?
Used to specify database retrievals and updates (insertion, deletion, and modification of data).
Examples include SELECT, INSERT, and UPDATE statements.
What is Data Control Language (DCL)?
Used to control and provide levels of access privileges and authorization to database objects.
What are the types of DBMS Interfaces? (9)
- Stand-alone query language interfaces
- Programmer interfaces for embedding DML
- User-friendly interfaces
- Forms-based interfaces
- Graphics-based interfaces
- Natural language interfaces
- Speech as Input and Output
- Parametric interfaces
- Interface for the DBA
Examples include menu-based interfaces popular for browsing on the web.
What is the function of a DDL Compiler?
Processes DDL statements and stores database description in the DBMS catalog.
What are Privileged Commands?
Commands used only by the DBA or the DBA staff for creating accounts, granting authorization, and changing database descriptions.
What does a Query Compiler do?
Parses queries, analyzes them for correctness, and compiles them into an internal form.
What is the role of a Query Optimizer?
Rearranges operations, eliminates redundancies, and uses correct algorithms during execution.
What does a Precompiler do?
Extracts DML commands from an application program.
What is a Runtime Database Processor?
Executes privileged commands, executable query plans, and canned transactions with runtime parameters.
What is a Centralized DBMS?
Combines everything into a single system including DBMS software, hardware, application programs, and user interface processing software.
What is a Client in a Client-Server DBMS architecture?
A user machine that provides user interface capabilities and local processing.
What distinguishes a Thin Client from a Thick Client?
- Thin client: Dependent on another machine to complete a process
- Thick client: Can provide functionality independent of the server.
What is a Two Tier Client-Server Architecture?
Client contains the user interface and application programs; server contains the DBMS.
What is a Three Tier Client-Server Architecture?
The client communicates with the application server, which stores business rules to access data from the database, while the database server provides the data.
What is a Database Schema?
The description of a database, including the structure, data types, and constraints.
What is the difference between Database Schema and Database State?
- Database Schema: Changes infrequently
- Database State: Changes every time the database is updated.
What are the types of Database States?
- Empty State
- Initial State
- Valid State (Current State)
What is Logical Data Independence?
The capacity to change the conceptual schema without changing the external schemas and their associated application programs.
What is Physical Data Independence?
The capacity to change the internal schema without changing the conceptual schema.
What are the categories of Data Models?
- Conceptual (high-level, semantic) data models
- Physical (low-level, internal) data models
- Implementation (representational) data models
What is a Conceptual Data Model?
Provides concepts that are close to the way many users perceive data.
What is a Physical Data Model?
Describes details of how data is stored in the computer, generally meant for computer specialists.
