Computer Science 360

Peripherals and File Design

Lecture 5

Chapter 4

· Continuation of Assignment #1 discussion

· How do we handle an n-way merge

· Object definitions

· Field & Record Organization

· Fields

· Streamed I/O – field boundaries may be lost

· Fields structures – meaningful collection of bytes

· Fixed length – wasted space

· Length prefix – overhead of length field

· Delimiter – may occur as data

· Keyword – overhead of keyword

· Record structures – meaningful collection of fields

· Fixed length – wasted space

· Predictable number of bytes

· Predictable number of fields

· Length prefix – overhead

· Secondary file of record addresses

· Delimiter at the end of each record

· File dump

· Character vs hexadecimal representations

· Use the LIST.COM (public domain) program (Email to you this morning) to examine the following records in a file:

Ames | John | 123 Maple | Stillwater | OK | 74075

Peck | Jack | 430 Edwards Hall | Clemson | SC | 29631-1906

®

· Record Key

· Identifier for a record

· Often will be distinct (unique) from keys in all other records (primary key)

· Sometimes will be duplicated (secondary key)

· Primary keys should be dataless (blind)