February 03, 2020
Amitraj
File Organization may be either physical file or a logical file.
1. Physical File - A physical file is a physical unit, such as magnetic tape or a disk.
2. Logical File - A logical file on the other hand is a complete set of records for a specific application or purpose. A logical file may occupy a part of physical file or may extend over more than one physical file.
Inverted List Method -
In file organization, this is a file that is indexed on many of the attributes of the data itself. The inverted list method has a single index for each key type. The records are not necessarily stored in a sequence. They are placed in the data storage area, but indexes are updated for the record keys and location.
Example:- In a company file, an index could be maintained for all products, another one might be maintained for product types. Thus, it is faster to search the indexes than every record.
-> These types of files are also known as "inverted indexes". Nevertheless, inverted list files use more media space and the storage devices get full quickly with this type of organization. The benefits are apparent immediately because searching is fast. however, updating is much slower.
-> Content based queries in text retrieval systems use inverted indexes as their preferred mechanism. Data items in these systems are usually stored compressed which would normally slow the retrieval process, but the compression algorithm will be chosen to support this technique.
1. Physical File - A physical file is a physical unit, such as magnetic tape or a disk.
2. Logical File - A logical file on the other hand is a complete set of records for a specific application or purpose. A logical file may occupy a part of physical file or may extend over more than one physical file.
Inverted List Method -
In file organization, this is a file that is indexed on many of the attributes of the data itself. The inverted list method has a single index for each key type. The records are not necessarily stored in a sequence. They are placed in the data storage area, but indexes are updated for the record keys and location.
Example:- In a company file, an index could be maintained for all products, another one might be maintained for product types. Thus, it is faster to search the indexes than every record.
-> These types of files are also known as "inverted indexes". Nevertheless, inverted list files use more media space and the storage devices get full quickly with this type of organization. The benefits are apparent immediately because searching is fast. however, updating is much slower.
-> Content based queries in text retrieval systems use inverted indexes as their preferred mechanism. Data items in these systems are usually stored compressed which would normally slow the retrieval process, but the compression algorithm will be chosen to support this technique.
