SEQOPT parameter

Summary

Default value

0

Parameter type

System

Where set

On User 0's parameter line

Related products

All

Introduced

Model 204 V6.1 or earlier

Description

The option for the prefetch (look-ahead read) feature

SEQOPT must be either zero or 1. If the default value of zero is used, the prefetch feature is disabled. If a value of 1 is specified, the prefetch feature is enabled.

The prefetch feature can produce performance improvements for applications containing FOR EACH RECORD statements. The prefetch feature is described in more detail in the Model 204 User Language Manual and the Model 204 System Manager's Guide.

The prefetch feature can also be controlled with the RESET command issued by a user having system manager privileges.

Use of the prefetch feature requires that the MAXBUF parameter be set large enough to accommodate the look-ahead reads. Without this setting, performance might worsen. The specification for the MAXBUF parameter is calculated by the following formula:

MAXBUF = NUSERS * (4 + 2 * (Maximum FOR EACH RECORD loop nest level)