UNIT-V
ADVANCED DBMS
Database Management System (DBMS) is software that allows access to data
stored in a database and provides an easy and effective method of –
Defining the information.
Storing the information.
Manipulating the information.
Protecting the information from system crashes or data theft.
Differentiating access permissions for different users.
Data Theft: When somebody steals the information stored on databases, and
servers, this process is known as Data Theft.
Note: Structure of Database Management System is also referred to as Overall
System Structure or Database Architecture but it is different from the tier
architecture of Database.
The database system is divided into three components: Query Processor,
Storage Manager, and Disk Storage. These are explained as following below.
Architecture of DBMS
1. Query Processor: It interprets the requests (queries) received from end
user via an application program into instructions. It also executes the user
,request which is received from the DML compiler.
Query Processor contains the following components –
DML Compiler: It processes the DML statements into low level instruction
(machine language), so that they can be executed.
DDL Interpreter: It processes the DDL statements into a set of table
containing meta data (data about data).
Embedded DML Pre-compiler: It processes DML statements embedded in
an application program into procedural calls.
Query Optimizer: It executes the instruction generated by DML Compiler.
2. Storage Manager: Storage Manager is a program that provides an
interface between the data stored in the database and the queries received. It
is also known as Database Control System. It maintains the consistency and
integrity of the database by applying the constraints and executing
the DCL statements. It is responsible for updating, storing, deleting, and
retrieving data in the database.
It contains the following components –
Authorization Manager: It ensures role-based access control, i.e,. checks
whether the particular person is privileged to perform the requested
operation or not.
Integrity Manager: It checks the integrity constraints when the database
is modified.
Transaction Manager: It controls concurrent access by performing the
operations in a scheduled way that it receives the transaction. Thus, it
ensures that the database remains in the consistent state before and after
the execution of a transaction.
File Manager: It manages the file space and the data structure used to
represent information in the database.
Buffer Manager: It is responsible for cache memory and the transfer of
data between the secondary storage and main memory.
3. Disk Storage: It contains the following components –
Data Files: It stores the data.
Data Dictionary: It contains the information about the structure of any
database object. It is the repository of information that governs the
metadata.
Indices: It provides faster retrieval of data item.
The structure of a Database Management System (DBMS) can be divided into
three main components: the Internal Level, the Conceptual Level, and the
External Level.
1. Internal Level: This level represents the physical storage of data in the
database. It is responsible for storing and retrieving data from the storage
devices, such as hard drives or solid-state drives. It deals with low-level
implementation details such as data compression, indexing, and storage
allocation.
2. Conceptual Level: This level represents the logical view of the database. It
deals with the overall organization of data in the database and the
relationships between them. It defines the data schema, which includes
, tables, attributes, and their relationships. The conceptual level is
independent of any specific DBMS and can be implemented using different
DBMSs.
3. External Level: This level represents the user’s view of the database. It deals
with how users access the data in the database. It allows users to view data
in a way that makes sense to them, without worrying about the underlying
implementation details. The external level provides a set of views or
interfaces to the database, which are tailored to meet the needs of specific
user groups.
The three levels are connected through a schema mapping process that
translates data from one level to another. The schema mapping process
ensures that changes made at one level are reflected in the other levels.
In addition to these three levels, a DBMS also includes a Database
Administrator (DBA) component, which is responsible for managing the
database system. The DBA is responsible for tasks such as database design,
security management, backup and recovery, and performance tuning.
Overall, the structure of a DBMS is designed to provide a high level of
abstraction to users, while still allowing low-level implementation details to be
managed effectively. This allows users to focus on the logical organization of
data in the database, without worrying about the physical storage or
implementation details.
Parallel DB
A parallel DBMS is a DBMS that runs across multiple processors or CPUs and is
mainly designed to execute query operations in parallel, wherever possible. The
parallel DBMS link a number of smaller machines to achieve the same
throughput as expected from a single large machine.
In Parallel Databases, mainly there are three architectural designs for parallel
DBMS. They are as follows:
1. Shared Memory Architecture
2. Shared Disk Architecture
3. Shared Nothing Architecture
Let’s discuss them one by one:
1. Shared Memory Architecture- In Shared Memory Architecture, there are
multiple CPUs that are attached to an interconnection network. They are able to
share a single or global main memory and common disk arrays. It is to be noted
that, In this architecture, a single copy of a multi-threaded operating system
and multithreaded DBMS can support these multiple CPUs. Also, the shared
memory is a solid coupled architecture in which multiple CPUs share their
memory. It is also known as Symmetric multiprocessing (SMP). This
architecture has a very wide range which starts from personal workstations that
support a few microprocessors in parallel via RISC.
ADVANCED DBMS
Database Management System (DBMS) is software that allows access to data
stored in a database and provides an easy and effective method of –
Defining the information.
Storing the information.
Manipulating the information.
Protecting the information from system crashes or data theft.
Differentiating access permissions for different users.
Data Theft: When somebody steals the information stored on databases, and
servers, this process is known as Data Theft.
Note: Structure of Database Management System is also referred to as Overall
System Structure or Database Architecture but it is different from the tier
architecture of Database.
The database system is divided into three components: Query Processor,
Storage Manager, and Disk Storage. These are explained as following below.
Architecture of DBMS
1. Query Processor: It interprets the requests (queries) received from end
user via an application program into instructions. It also executes the user
,request which is received from the DML compiler.
Query Processor contains the following components –
DML Compiler: It processes the DML statements into low level instruction
(machine language), so that they can be executed.
DDL Interpreter: It processes the DDL statements into a set of table
containing meta data (data about data).
Embedded DML Pre-compiler: It processes DML statements embedded in
an application program into procedural calls.
Query Optimizer: It executes the instruction generated by DML Compiler.
2. Storage Manager: Storage Manager is a program that provides an
interface between the data stored in the database and the queries received. It
is also known as Database Control System. It maintains the consistency and
integrity of the database by applying the constraints and executing
the DCL statements. It is responsible for updating, storing, deleting, and
retrieving data in the database.
It contains the following components –
Authorization Manager: It ensures role-based access control, i.e,. checks
whether the particular person is privileged to perform the requested
operation or not.
Integrity Manager: It checks the integrity constraints when the database
is modified.
Transaction Manager: It controls concurrent access by performing the
operations in a scheduled way that it receives the transaction. Thus, it
ensures that the database remains in the consistent state before and after
the execution of a transaction.
File Manager: It manages the file space and the data structure used to
represent information in the database.
Buffer Manager: It is responsible for cache memory and the transfer of
data between the secondary storage and main memory.
3. Disk Storage: It contains the following components –
Data Files: It stores the data.
Data Dictionary: It contains the information about the structure of any
database object. It is the repository of information that governs the
metadata.
Indices: It provides faster retrieval of data item.
The structure of a Database Management System (DBMS) can be divided into
three main components: the Internal Level, the Conceptual Level, and the
External Level.
1. Internal Level: This level represents the physical storage of data in the
database. It is responsible for storing and retrieving data from the storage
devices, such as hard drives or solid-state drives. It deals with low-level
implementation details such as data compression, indexing, and storage
allocation.
2. Conceptual Level: This level represents the logical view of the database. It
deals with the overall organization of data in the database and the
relationships between them. It defines the data schema, which includes
, tables, attributes, and their relationships. The conceptual level is
independent of any specific DBMS and can be implemented using different
DBMSs.
3. External Level: This level represents the user’s view of the database. It deals
with how users access the data in the database. It allows users to view data
in a way that makes sense to them, without worrying about the underlying
implementation details. The external level provides a set of views or
interfaces to the database, which are tailored to meet the needs of specific
user groups.
The three levels are connected through a schema mapping process that
translates data from one level to another. The schema mapping process
ensures that changes made at one level are reflected in the other levels.
In addition to these three levels, a DBMS also includes a Database
Administrator (DBA) component, which is responsible for managing the
database system. The DBA is responsible for tasks such as database design,
security management, backup and recovery, and performance tuning.
Overall, the structure of a DBMS is designed to provide a high level of
abstraction to users, while still allowing low-level implementation details to be
managed effectively. This allows users to focus on the logical organization of
data in the database, without worrying about the physical storage or
implementation details.
Parallel DB
A parallel DBMS is a DBMS that runs across multiple processors or CPUs and is
mainly designed to execute query operations in parallel, wherever possible. The
parallel DBMS link a number of smaller machines to achieve the same
throughput as expected from a single large machine.
In Parallel Databases, mainly there are three architectural designs for parallel
DBMS. They are as follows:
1. Shared Memory Architecture
2. Shared Disk Architecture
3. Shared Nothing Architecture
Let’s discuss them one by one:
1. Shared Memory Architecture- In Shared Memory Architecture, there are
multiple CPUs that are attached to an interconnection network. They are able to
share a single or global main memory and common disk arrays. It is to be noted
that, In this architecture, a single copy of a multi-threaded operating system
and multithreaded DBMS can support these multiple CPUs. Also, the shared
memory is a solid coupled architecture in which multiple CPUs share their
memory. It is also known as Symmetric multiprocessing (SMP). This
architecture has a very wide range which starts from personal workstations that
support a few microprocessors in parallel via RISC.
