Page 102 - Accounting Information Systems

CHAPT E R 2 Introduction to Transaction Processing 73

FI GUR E
2-31 BATCH PROCESSING WITH REAL-TIME DATA COLLECTION

Sales Department Computer Operations Other Departments

Real-Time
Process

Inventory
Customer AR Sub
Sub

Data Input
Sales Data Input and Edit
Order Terminal Program

Sales
Invoice Orders

Batch Process
Customer
Sales
Journal

Update
and Report
Program

General Ledger
Accounts

User
Documents

Smith’s account does not prevent Mary Jones from accessing her account. Updating the inventory subsid-
iary record is almost unique. Because it is possible that both Mary Jones and John Smith are independ-
ently purchasing the same item at the same time, Mary Jones may be kept waiting a few seconds until
John Smith’s transaction releases the lock on the inventory account. This will be a relatively rare event,
and any such conflicts will be of little inconvenience to customers. As a general rule, therefore, master