What is the difference between logical and physical data?

The main difference between Logical and Physical Data Model is that Logical data models help to define the data elements and their relationships, while the physical data models help to design the actual database based on the requirements gathered during the logical data modelling.

What is the difference between logical and physical schema?

Physical schema represents the actual connection to the data source or data target. Logical schema represents the logical name associated to that source or target.

What is data independence explain logical data independence and physical data independence with respect to three layer architecture of DBMS?

Data independence can be explained using the three-schema architecture. 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.

What is physical data independence and why is it important?

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.

What is the difference between logical index and physical index?

A physical index is the actual indexing structure as it is stored on disk. A logical index is a reference to a physical index. When you create a primary key, secondary key, foreign key, or unique constraint, the database server ensures referential integrity by creating a logical index for the constraint.

What is logical data independence and why is it important?

Logical data independence is the ability to modify the logical schema without causing application programs to be rewritten. Modifications at the logical level are necessary whenever the logical structure of the database is altered (for example, when money-market accounts are added to banking system).

What is logical database and physical database?

A logical database must be able to access and identify all files within the storage system to operate correctly, whereas a physical database manages a much smaller field of information. Sometimes, a physical database stores only a single file with one value or word in it.

How are different schema layers related to the concepts of logical and physical data independence?

Logical data independence means changes in the external schema do not necessarily cause changes in the conceptual schema, and vice versa. Physical data independence means that changes in the physical schema do not necessarily cause changes in the conceptual schema.

What is logical data independence Mcq?

Logical Data Independence: The ability to change the conceptual schema without having to change the view level schema. Physical Data Independence: The ability to change the internal schema without having to change the conceptual schema.

What is the difference between physical order and logical order?

Physical order is the order in which messages arrive on a queue. Logical order is when all of the messages and segments within a group are in their logical sequence, next to each other, in the position determined by the physical position of the first item belonging to the group.

What is physical order SQL?

The physical order is the way the data is stored on disk, which mostly is not ordered. The logical order is the order defined by the index. To find out if your SQL Server indexes are fragmented you can use a tool like SQL Index Manager or ApexSQL Discover, see overview here: free-tools-for-sql-server[^]

What are logical data independence and physical data independence What is the difference between them which of these harder to realize why?

The physical data independence is basically used to separate conceptual levels from the internal/physical levels….Difference between Physical and Logical Data Independence :

What is physical data independence?

Data independence is the type of data transparency that matters for a centralized DBMS . It refers to the immunity of user applications to changes made in the definition and organization of data. Physical data independence deals with hiding the details of the storage structure from user applications.

What is logical independence?

The logical data independence is the key feature of database management system for maintaining data integrity and for maintaining overall effectiveness of data usage.

What is physical independence in database?

Physical data independence is present in most databases and file environment in which hardware storage of encoding, exact location of data on disk, merging of records, so on this are hidden from user. One of the biggest advantage of databases is data independence.

What is physical data modeling?

Physical Data Model Options. A physical data model (or database design) is a representation of a data design as implemented, or intended to be implemented, in a database management system. In the lifecycle of a project it typically derives from a logical data model, though it may be reverse-engineered from a given database implementation.