What is difference between logical file and physical file?
* Physical file (PF) contains the data and have only one record
format. Logical file (LF) is a view of the physical file which does
not contain any data may be based on one physical file or more then
one physical file. Logical file can have more then one record
format. Logical can be non join or join logical file. Performance
becomes better if you use the logical file in the program.