Physical Data Independence : Physical Data Independence is defined as the ability to make changes in the structure of the lowest level of the Database Management System (DBMS) without affecting the higher-level schemas. Hence, modification in the Physical level should not result in any changes in the Logical or View levels.
What is data independence of DBMS?
What is Data Independence of DBMS? Data Independence can be defined as the ability of the data such that change in the schema at one level of the database without having to change the schema at the next higher level.
What is physical data independence and how do I use it?
Index on the first column of Students. Physical data independence helps you to separate conceptual levels from the internal/physical levels. It allows you to provide a logical description of the database without the need to specify physical structures.
What is meant by physical independence?
Physical data independence is achieved by the presence of the internal level of the database and then the transformation from the conceptual level of the database to the internal level. Due to Physical independence, any of the below change will not affect the conceptual layer.
What are the two types of data independence?
There are two types of data independence: 1 Logical Data Independence#N#Logical data independence refers characteristic of being able to change the conceptual... 2 Physical Data Independence More ...
How is Physical Data Independence achieved?
Physical Data Independence is achieved by modifying the physical layer to logical layer mapping (PL-LL mapping). We must ensure that the modification we have done is localized.
Why do we want to do any sort of data modification in the physical level?
This is because we may want to add or remove files and indexes to enhance the performance of the database system and make it faster. Hence, in this way, the Physical Data Independence enables us to do Performance Tuning. Ideally, when we change the physical level, we would not want to alter the logical and view level.
What is Codd's rule of logical data independence?
Codd’s Rule of Logical Data Independence says that users should be able to manipulate the Logical View of data without any information of its physical storage. Software or the computer program is used to manipulate the logical view of the data.
What is physical data independence?
Physical Data Independence means changing the physical level without affecting the logical level or conceptual level. Using this property, we can change the storage device of the database without affecting the logical schema.
What is a database administrator?
Database administrator is the one who decides what information is to be kept in the database and how to use the logical level of abstraction. It provides the global view of Data. It also describes what data is to be stored in the database along with the relationship.
How many levels of data independence are there?
There are two levels of data independence based on three levels of abstraction. These are as follows −
What is a database update?
Adding, deleting, or updating any new attribute, entity or relationship in the database.
What is logical data independence?
Logical data independence is a kind of mechanism, which liberalizes itself from actual data stored on the disk. If we do some changes on table format, it should not change the data residing on the disk.
What is metadata in a database?
A database system normally contains a lot of data in addition to users’ data. For example, it stores data about data, known as metadata, to locate and retrieve data easily. It is rather difficult to modify or update a set of metadata once it is stored in the database.
What is logical data?
Logical data is data about database, that is, it stores information about how data is managed inside. For example, a table (relation) stored in the database and all its constraints, applied on that relation. Logical data independence is a kind of mechanism, which liberalizes itself from actual data stored on the disk.
What is metadata architecture?
Metadata itself follows a layered architecture, so that when we change data at one layer, it does not affect the data at another level. This data is independent but mapped to each other.
What happens if a database is not multi-layered?
If a database system is not multi-layered, then it becomes difficult to make any changes in the database system. Database systems are designed in multi-layers as we learnt earlier.
Why is data independence important in DBMS?
Data Independence in DBMS is useful to modify the Database schema at one level of a database system and it will not change the Database schema at the succeeding higher level. Data independence help to keep data separate/independent from all programs that are using the database.
What is physical data independence?
Physical data independence permits to delivery of a logical description of the database without the need to specify the physical structures. If we want to achieve physical data independence, then it’s easy to achieve as compared to Logical Data Independence.
Does switching to different data structures affect conceptual layer?
Switching to different data structures will not affect the conceptual layer.
Does compression affect conceptual layer?
If we change the hashing algorithms or compression techniques, then it will not affect the conceptual layer.
Is it hard to achieve logical data independence?
Its very difficult to achieve logical data independence as compared to Physical Data independence.
Does physical independence affect conceptual layer?
Due to Physical independence, any of the below changes will not affect the conceptual layer.
Is email only for business?
3. Email is only for Advertisement/business enquiries.
How does Data Independence Work in DBMS?
This huge data quantity makes it complicated to update or alter the database contents in a frequent manner. As a part of scalability and database expansion, this property of the system necessitates the call for fulfilling the database required to hold the property that allows the existing data and contents to stay unmodified when there are changes made on the top tiers of the DBMS system.
What is logical data independence?
Logical Data Independence is the distinctive property of the database system to be capable of updating the logic behind the logical level of the structure or schema devoid of disturbing the other layers of the schema and functions inside the database management system. In this type of Data Independence, the outside appearances of the table’s contents are not involved by the modifications performed by the view level of the schema in the database system. The modifications that one can possibly apply on the logical layer of the schema can cover the basic operations like the insert, delete and update operations, as well as the complicated table related operations like truncate, Union, Minus, Intersect, etc.
What is data independence in a database?
Data Independence in the Database Management System (DBMS) is an essential criterion to be kept in check while designing and managing the databases and their respective schema. It can be defined as the ability of the data in one schema not to be affected whenever there is an update or modify operation performed on the other schema in the database system. It is usually applied to the three-tiered Database Architecture systems, where the data from the bottom tier are expected to be not distressed in the events of modifications performed on the other tiers on the top of the system.
Why is data independence important?
The purposes of instilling Data Independence on to the Database Management System are for maintaining the functional behavior of the database system, enhanced security of the system , keeping the boundaries clear between the three levels of the database schema, performing application maintenance without the extra cost being spent, etc.
What is the physical level of a database?
The Physical level can be defined as the physical storage space allocated for the data to be stored and can be pulled out whenever there is a requirement for the data. This level is considered to be the lowermost layers in the database architecture. Next, the Logical level can be defined as the contents of the database, in the structure of tables, ...
What is data independence?
Data independence refers characteristic of being able to modify the schema at one level of the database system without altering the schema at the next higher level. There are two types of data independence: 1. Logical Data Independence.
What happens if we change the conceptual view of the data?
If we do any changes in the conceptual view of the data, then the user view of the data would not be affected.
Where does physical data independence occur?
Physical data independence occurs at the logical interface level.
What Is Data Independence of DBMS?
Types of Data Independence
- In DBMS there are two types of data independence 1. Physical data independence 2. Logical data independence.
Levels of Database
- Before we learn Data Independence, a refresher on Database Levels is important. The database has 3 levels as shown in the diagram below 1. Physical/Internal 2. Conceptual 3. External Consider an Example of a University Database. At the different levels this is how the implementation will look like:
Physical Data Independence
- Physical data independence helps you to separate conceptual levels from the internal/physical levels. It allows you to provide a logical description of the database without the need to specify physical structures. Compared to Logical Independence, it is easy to achieve physical data independence. With Physical independence, you can easily change the physical storage structur…
Logical Data Independence
- Logical Data Independence is the ability to change the conceptual scheme without changing 1. External views 2. External API or programs Any change made will be absorbed by the mapping between external and conceptual levels. When compared to Physical Data independence, it is challenging to achieve logical data independence.
Importance of Data Independence
- Helps you to improve the quality of the data
- Database system maintenance becomes affordable
- Enforcement of standards and improvement in database security
- You don’t need to alter data structure in application programs
Summary
- Data Independence is the property of DBMS that helps you to change the Database schema at one level of a database system without requiring to change the schema at the next higher level.
- Two levels of data independence are 1) Physical and 2) Logical
- Physical data independence helps you to separate conceptual levels from the internal/physic…
- Data Independence is the property of DBMS that helps you to change the Database schema at one level of a database system without requiring to change the schema at the next higher level.
- Two levels of data independence are 1) Physical and 2) Logical
- Physical data independence helps you to separate conceptual levels from the internal/physical levels
- Logical Data Independence is the ability to change the conceptual scheme without changing
Data Independence
- A database system normally contains a lot of data in addition to users’ data. For example, it stores data about data, known as metadata, to locate and retrieve data easily. It is rather difficult to modify or update a set of metadata once it is stored in the database. But as a DBMS expands, it needs to change over time to satisfy the requirements o...
Logical Data Independence
- Logical data is data about database, that is, it stores information about how data is managed inside. For example, a table (relation) stored in the database and all its constraints, applied on that relation. Logical data independence is a kind of mechanism, which liberalizes itself from actual data stored on the disk. If we do some changes on table format, it should not change the data re…
Physical Data Independence
- All the schemas are logical, and the actual data is stored in bit format on the disk. Physical data independence is the power to change the physical data without impacting the schema or logical data. For example, in case we want to change or upgrade the storage system itself − suppose we want to replace hard-disks with SSD − it should not have any impact on the logical data or sche…