Consultor Eletrônico

Performance issue on AS/400

920505-aab01
DRAFT COPY - Currently under review and edit.


INTRODUCTION:
=============

Performance problems accessing data files on AS/400 using Progress.


POSSIBLE CAUSE:
===============

Logical file or join created with MAINT parameter for access path
set to either *REBLD or *DLY.


PROCEDURAL APPROACH:
====================

When a logical file is first created with the CRTLF command there are
three optional ways to have it maintained. This is determined by the
MAINT option off CRTLF. Below is a brief description of the
functionality of each of the options:

CRTLF MAINT(*IMMED): The access path is continuously (immediately)
maintained for each logical file member, whether
the logical file member is opened or closed.
Note the *IMMED must be specified for all files
requiring unique keys.

CRTLF MAINT(*REBLD): The access path is completely rebuilt when a
logical file member is opened during the run of
a program. The access path is continuously
maintained until the the member is closed; the
access path maintenance is then ended.

CRTLF MAINT(*DLY): The maintenance of the access path is delayed
until the logical file member is opened for
use;then the access path is changed only for
records that have been deleted, added or
changed since the file was last opened.

If the files already exists on the system you can determine what
option was used for logical file access path maintenance with the
following OS/400 command:

DSPFD FILE(filename)

After executing this command there are several pages of text, the
MAINT option is on the second page.

The performance problem occurs when you have the maint option set to
either *REBLD or *DLY. We advocate using *IMMED for the best
results.


REFFERENCES TO WRITTEN DOCUMENTATION:
=====================================

For Complete details on the use of CRTLF and DSPFD, refer to the
AS/400 documentation set.

Progress Software Technical Support Note # 5766