iX V6.5 (30391-90011)

Chapter 3 73

Deﬁning a Database

Set Part

The number of entries deﬁned, or the entries calculated from the percent,

cannot exceed the maximum entry count minus the initial allocation. The

increment is adjusted to represent an even multiple of the blocking factor.

The increment is an optional parameter. If the increment is not speciﬁed

for the data set, or is zero, but the initial capacity is greater than zero,

then the increment for each expansion is defaulted to ten percent (10%) of

the initial capacity for the data set. If the initial capacity is equal to the

maximum capacity, or the initial capacity is zero, then this indicates the

data set cannot be expanded and increment is ignored.

Examples

NAME: SUP-MASTER,MANUAL /INDEXED (13/12,18),DISC1;

ENTRY: SUPPLIER(1),

STREET-ADD,

CITY,

STATE,

ZIP;

CAPACITY: 2001,501,20%;

Description

The example also shows the data set SUP-MASTER which will reside on Disc1. Assigning

the device class where a data set will reside can provide greater performance for the

TurboIMAGE/XL database and can aid in better use of system resources. An

understanding of how to spread the data sets over multiple disk devices can be obtained

from your system manager. Your system manager will be able to give you a listing of logical

devices and their corresponding device class names (each logical device can have up to

eight names).

To retrieve information on where each data set resides after specifying device classes in

the schema, you can use the MPE/iX command LISTF,3 (after the database is created).

This command lists the device type, logical device number, and the device class name for

each data set in the database. The DBUTIL >>SHOW command can also be used to display

the devices on which data sets reside.

The data set SUP-MASTER will have a B-Tree index created on the key item, SUPPLIER.

B-Tree DBFINDs can be done using SUPPLIER for SUP-MASTER. Also, B-Tree DBFINDs

will be allowed using all of its corresponding search items in the detail sets. In the above

example, SUPPLIER has only one path. Hence, B-Tree DBFIND can be done using the

related search item and the detail data set. The presence of capacity expansion parameters

indicate that it is enabled for dynamic data set expansion.

The example also shows that the maximum capacity is 2001, the initial capacity is 501,

and the increment is 20%.

Another example is capacity deﬁned as follows:

CAPACITY: 2001,501,25;

The maximum capacity is set at 2001, has an initial capacity of 501, and will be

automatically expanded by 25 when the initialized space is exhausted.

To allow dynamic expansion for a master data set, specify the maximum capacity and the

initial capacity when deﬁning the data set. If dynamic expansion is not needed for the data