With neat sketch explain the overall database system structure?

Answer 1

Overall System Structure

1. Database systems are partitioned into modules for different functions. Some functions (e.g. file systems) may be provided by the operating system.

2. Components include:

o File manager manages allocation of disk space and data structures used to represent information on disk.

o Database manager: The interface between low-level data and application programs and queries.

o Query processor translates statements in a query language into low-level instructions the database manager understands. (May also attempt to find an equivalent but more efficient form.)

o DML precompiler converts DML statements embedded in an application program to normal procedure calls in a host language. The precompiler interacts with the query processor.

o DDL compiler converts DDL statements to a set of tables containing metadata stored in a data dictionary.

In addition, several data structures are required for physical system implementation:

o Data files: store the database itself.

o Data dictionary: stores information about the structure of the database. It is used heavily. Great emphasis should be placed on developing a good design and efficient implementation of the dictionary.

o Indices: provide fast access to data items holding particular values.

Answer 2

The overall database system structure consists of three main components: the external level, the conceptual level, and the internal level.

The external level deals with the user's view of the database and defines how users interact with the system through views or user interfaces.

The conceptual level represents the logical structure of the entire database and defines the data and relationships between them using a data model. It serves as an intermediary between the external and internal levels.

The internal level involves the physical storage and implementation of the database on the computer system, including data storage structures, indexing techniques, and access methods. It is responsible for efficient data retrieval and storage.