IBM Informix Developer's Handbook - IBM Redbooks

Consider using buffered logging only if the following situations:
► If the database is updated frequently (speed of updating is important).
► If the application that is performing the transaction can continue as it is and if
you decide that the price (in time and effort) of returning the database to a
consistent state by either removing the effects or reapplying the transaction is
too high or you can re-create the updates in the event of failure.
If a transaction failure does occur, you can simply choose to leave the
database in its inconsistent state if the transaction does not significantly affect
database data.
As you consider whether to use a buffered or unbuffered logging method,
remember that no automatic process or utility can perform a rollback of a
committed transaction or can commit part of a transaction that has been rolled
back. Without detailed knowledge of the application, messages are not enough
to determine what has happened. Based on your knowledge of your application
and your system, you might need to help the DBA determine when to roll back or
to follow though on interrupted transactions. For more information about this
topic, see the Guide to SQL: Tutorial section on interrupted modifications, which
is available at:
http://publib.boulder.ibm.com/infocenter/idshelp/v115/index.jsp?topic=/com.ibm.
sqlt.doc/ids_sqt_277.htm
1.3.2 Informix developer environment
The environment references that you need have some variations, depending on
whether you use the IBM common client API or the native Client SDK and which
operating system you use. The environment settings must include identifying the
following references to the components:
► Setting the INFORMIXDIR environment variable to the installation directory of
the software installation location.
► Setting up Informix Server information (INFORMIXSERVER).
► Adding the $INFORMIXDIR/bin to the PATH environment variable.
On Windows, you have to set only the Informix database server information with
the setnet32.exe utility. On UNIX-type platforms, you might want to set the
environment variables so that they are set in your user profile at login or use a
setup script. You also need to reference the sqlhosts file to identify Informix
Server information. In the chapters that follow, we explain how to install the
server and provide specific details for the relevant API environment details.
Chapter 1. Introduction to IBM Informix 21