Documentation Notes for the

IBM Informix JDBC Driver Programmer's Guide

Date: 6 June 2003

Version: 2.21


Table of Contents

I. Overview
II. Documentation Notes and Corrections

I. Overview

In addition to the features documented in the release notes, this document describes feature and performance topics not covered in the IBM Informix JDBC Driver Programmer's Guide or modified since publication.

II. Documentation Notes and Corrections

A. New IFX_PAD_VARCHAR Environment Variables

A new IFX_PAD_VARCHAR environment variable can be used to control how
Dynamic Server sends and receives VARCHAR or NVARCHAR data types.

When IFX_PAD_VARCHAR is set to 0, only the portion of a VARCHAR or
NVARCHAR value that contains data is sent to or from the server. For example,
to send the string "ABC" from a column declared as VARCHAR(255),
only three (3) bytes would be transmitted using the 0 setting.

When IFX_PAD_VARCHAR is set to 1, the entire data structure that holds the
value is transmitted, or 255 bytes in the previous example.

The effect of the IFX_PAD_VARCHAR setting on performance is context-sensitive.
When transmitting data over a low-bandwidth network, for example, the 0 setting
might improve performance by reducing the total amount of transmitted data. In
a high-bandwidth network, however, a setting of 1 might improve performance,
if the amount of CPU time required to process variable-length packets were
greater than the time that was required to send the entire character stream.




Copyright © 2003, IBM Software, Inc. All rights reserved