File Processing : File Organization

1
File Processing File Organization

• 2005, Spring
• Pusan National University
• Ki-Joune Li

2
Logical Structure of File
File
Field
Field
Field
Record (Tuple)
Record
Record
Block
3
Fixed Size Record

• Fixed Size
• Fixed Number of Fields, and
• Fixed Size of each Field
• Easy to implement
• Disk Address
• (n-1)srecord
• Deletion of a record
• Like Array but no movement
• Free Record List or
• Pointer to Next Record

4
Variable Length Record

• Variable Length due to
• Variable Number of Fields, or
• Variable Size of each Field
• Complicated to implement
• Implementation
• Delimiter (, size, or pointer)
• Slotted Page
• Fixed Length
• Overflow Area
• Reserved Space

5
Delimiters
Record
Record

Record
Record
Record

Record

• Difficult to handle deletions and insertions

6
Slotted Page

• Records can be moved around within a page
• to keep them contiguous with no empty space
  between them
• entry in the header must be updated.

• Pointers should not point directly to record
• But to the entry for the record in header.

7
Reserved Space
8
Overflow Area
9
Binary Large Object Block (BLOB)

• If size (field) gt size (block)
• e.g. Image or Video
• BLOB Type of field where its size is greater
  than block size
• cf. CLOB Text rather than binary

Name
ID
Photo