Batch Processing

Processing where a number of transactions are collected together and then input and processed together is called batch processing. For example the large banks batch process cheques.

At the end of the day there will be a large number of cheques from a given branch. These will be put into a batch and a cover slip attached. A clerk will obtain a batch number which will be unique to this batch and the batch number will be entered in the branches batch register. The clerk will calculate and write on the batch slip two or more batch totals. These are the total number of documents in the batch and the totals of any important fields.

The data is then sent to the computer department for data preparation. The batch totals will also be prepared for input. When the data is input the computer will calculate the batch control totals from the input. Finally the newly calculated values will be compared with the values calculated by the clerk. The process of comparison between the two sets of values is called reconciliation. If the control totals do not reconcile then there must have been an error. This could be due to a missing document, an error in data preparation or an error in the original calculation of the control totals. The source of the error will be traced and appropriate action taken.

Master files and transaction files

Master file

This is a collection of records holding information about an entity such as a person or good.

Example: An employee payroll master file will contain a record for each employee, with fields holding an employee’s surname, first name, address, department, etc. These fields will not change very often – maybe once or twice a year. In addition, there will be fields which change regularly – fields such as gross pay to date (since the start of the tax year), tax paid to date, N.I. contributions to date.

Transaction file

Holds information about events occurring in the organisation. For employee payroll file, basically three kinds of transactions: Those involving hourly, weekly or monthly payments and those involving changes in emploee details.

• Weekly / fortnightly transaction file with information of hours worked – used to calculate employees wages.
• When new employee is hired, new record must be added
• When employee leaves, their record is deleted
• Employee may change address, bank account, etc. a record muct be ammended

Stages in batch processing

Typical, large-scale batch system where data is collected on paper documents (such as applications for renewal of a TV or driver’s licence) has following stages:

1. The paper documents are collected into batches of say 50, checked, control totals and hash totals calculated and written on a batch header document.
2. The data is keyed in off-line and validated by a computer program. It is stored on a transaction file.
3. The data is verified by being entered a second time by a different operator. Any discrepancies are reconciled.
4. Transaction file is transferred to the main computer. This may be physically or electronically between computers.
5. Processing begins at a scheduled time – maybe overnight when the computer is not busy dealing with on-line users. All the processing steps (beginning with the next) can take place without operator intervention.
6. Transaction file may be sorted into same sequence as master file to speed up the processing of the data.
7. The master file is updated.
8. Any required reports are produced.

An account of the batch processing of cheques is in the banks case study.

© LEV