Database systems are partitioned into modules for different functions. Some functions may be provided by the operating system. The components include;
1. File manager : Its manages allocation of disk space and data structures used to represent information on disk.
2. Database manager : The interface between low-level data and application programs and queries.
3. Query processor : Its translates statement in a query language into low-level instruction the database manager understands.
4. 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.
5. DDL Compiler : Converts DDL statements to a set of tables containing metadata stored in a data dictionary.
6. Data Files : Store the database itself.
7. 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.
8. Indices : provide fast access to data items holding particular values.
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