Transcript Document 7901570

File Processing : File
Organization
2005, Spring
Pusan National University
Ki-Joune Li
PNU
STEM
Logical Structure of File
Field
Field
Field
Record (Tuple)
Fixed Size Record
Record
Record
Block
File
Variable Size Record
PNU
STEM
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
PNU
STEM
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
PNU
STEM
Delimiters
Record
Record
…
Delimiters
Record
Record
Record
Pointer/Size
• Difficult to handle deletions and insertions
…
Record
PNU
STEM
Slotted Page
Pointer to Record
 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.
PNU
STEM
Reserved Space
Maximum # of Fields
PNU
Overflow Area
First field of record
Rest records
STEM
PNU
STEM
Binary Large Object Block (BLOB)

If size (field) > size (block)

e.g. Image or Video
Name
ID#
Photo
Block size

BLOB : Type of field where its size is greater than block size

cf. CLOB : Text rather than binary
Name
ID#
Contiguous Reserved
Block for BLOB