logical data : refer to the immunity of the external scheme towards changes in the conceptual scheme.
physical data: refer to the immunity of the conceptual scheme towards changes in the internal scheme.
The ability to modify a scheme definition in one level without affecting a scheme definition in next higher level is called data independence there are two types of data independence physical data independence:- refers to the ability to modify the scheme followed at the physical level without affecting the scheme followed at logical level logical data independence:- refers to the ability to modify the conceptual scheme without affecting the schemes followed at view level logical independence is difficult to achieve
While physical tags are also referred to as presentational mark-up, logical tags are useless for appearances. Physical tags are newer versions while logical tags are old and concentrate on content.
For a physical Data Flow Diagram you explore into the logical DFD. for example, if you have a data flow arrow declared as "customer information" now the physical DFD would include in that data flow arrow "customer information = customer_name + customer_address". something along these lines Physical DFD shows how various functions are performed and who does them but Logical DFD strips away all physical constraints but does not restrict physical happenings from taking place.
Conceptual designs attempts to identify the highest level of relationships between entities. Conceptual designs include only important entities. Physical design helps in converting the logical design into the physical form.
In the 8086/8088 the physical address and logical address have the same importance, because they both relate to the address of the operand. It is true that the offset (logical) address is added to the segment address to determine the physical address, but the limitations of the architecture of the processor forces programmers to consider both.If you are talking about a virtual environment, however, such as in the 80286 or higher, then the logical address is more important than the physical address, because the logical address is the address of the operand, while the physical address is (somewhat) arbitrarily assigned by the operating system.
the logical data independence is hard to achieve because all the manipulation is belonging in logical data independence but in physical data independence only show the physical view .
It is generally considered more difficult to achieve logical data independence compared to physical data independence. Logical data independence involves separating the conceptual structure of the data from the physical storage aspects, which can be complex depending on the database design. Physical data independence primarily deals with shielding the application from changes in the storage structure, which is usually more straightforward to achieve.
Logical data independence is considered more difficult than physical data independence because it involves changes to the conceptual schema and external schema, which are more closely tied to the way data is organized and viewed in the application. Physical data independence, on the other hand, deals with changes to the internal schema, which is more abstract and can be modified with less impact on the overall system.
difference between physical and logical data flow diagrams.
The logical data independence is the ability to modify a logical schema without making external view or application program change. The physical data independence is the ability to modify a physical schema without making external view or application prrogram change.
Hi, Data Independence refers to the immunity of user application to make changes in the definition and organization of Data. There are three types of Data Independence - 1. Logical Data Independence - The ability to change the logical (conceptual) schema without changing the External schema (User View) is called logical data independence. 2. Physical Data Independence - The ability to change the physical schema without changing the logical schema is called physical data independence. 3. View Data Independence - always independent,no effect.
Logical data independence refers to the ability to modify the conceptual schema without changing the external schemas or application programs. In contrast, physical data independence allows changes to the internal schema – like indexes and storage structures – without affecting the conceptual or external schemas.
Logical Data Independence : The ability to change the logical schema without changing the external schema or application programs is called as Logical Data Independence.Physical Data Independence : The ability to change the physical schema without changing the logical schema is called as Physical Data Independence.Logical Data Independence :being able to maintain change at external layer without having to make any change at the concept.Physical Data Independence : we want to be able to make any change on the conceptual level to deal without any change at the physical
The internal schema represents the physical storage structure of data, the external schema represents how different users view the data, and the conceptual schema defines the logical structure of the entire database. Logical data independence means that the conceptual schema can change without affecting the external schemas, while physical data independence means that changes in the physical storage structures do not affect the conceptual or external schemas.
In record design we distinguish between logical and physical records. LOGICAL RECORDS: A logical record maintains a logical relationship among all the data items in the records.It is the way the programmer or user sees the data.IN CONTRAST, A PHYSICAL RECORD is the way data are recorded on a storage medium.The programmer doesnt know about the physical map on the disk.The software presents the logical record in the required sequence.The capability is unique to the data base design. This question is answered by Silpa Sonali Sahoo.I request all the User if you can give some extra knoweldge/idea based on the discussed topic then you are most welcome.
The logical data independence is the ability to modify a logical schema without making external view or application program change. The physical data independence is the ability to modify a physical schema without making external view or application prrogram change.
Logical topologies consist of virtual connections between nodes.