TurboIMAGE/XL Database Management System Reference Manual (30391-90012)

Chapter 4 103
Using the Database
Entering Data in the Database
Figure 4-1. Sample Data Entries from ORDERS Database
Coordinating Additions to a Database
A single DBPUT call involves chain maintenance and other activity that can span multiple
data sets and multiple blocks within data sets even if an application is only adding entries
to a single data set. TurboIMAGE/XL coordinates calls to DBPUT to ensure that one
database user's DBPUT activity does not interfere with calls made by other users accessing
the same database. Each DBPUT request finishes processing before TurboIMAGE/XL moves
on to the next one. DBPUT calls are serialized even if they access unrelated data sets.
TurboIMAGE/XL provides a data prefetching option to enhance DBPUT (and DBDELETE)
processing. You can enable this option with the DBUTIL utility and are recommended to do
so only when all of the following conditions are true:
• Multiple processes are accessing the database.
• The processes are adding data with the DBPUT intrinsic (or deleting data with the
DBDELETE intrinsic).
• Adequate CPU and memory resources are available on your system.
For additional information, refer to the discussion of DBPUT in chapter 5 and the
description of the DBUTIL >>ENABLE command in chapter 8.
Access Mode and User Class Number
An entry cannot be added to a data set unless the user class number established when the
database is opened grants write access to the data set. The user class number must be in
the data set write class list.
The database must also be opened with an access mode allowing entries to be added. These
access modes are 1, 3, and 4. If it is opened with access mode 1, the DBLOCK procedure must