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

76 Chapter3
Defining a Database
Set Part
cannot exceed the maximum entry count minus the initial allocation. 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.
Example
NAME: SALES,DETAIL(11/14,18),DISC1;
ENTRY: ACCOUNT(CUSTOMER(PURCH-DATE)),
STOCK#(!PRODUCT),
QUANTITY,
PRICE,
TAX,
TOTAL,
PURCH-DATE (DATE-MASTER),
DELIV-DATE (DATE-MASTER);
CAPACITY: 1008,504,112;
Description
The example above shows the detail data set SALES which will reside on Disc1. The
maximum capacity is 1008, the initial capacity is 504, and the increment is 112.
Another example is a detail data set defined as follows:
CAPACITY: 500000(10),10000,25%;
The maximum capacity is set at 500000 with a blocking factor of 10. It has an initial
capacity of 10000, but will be automatically expanded by 2500 when the initialized space is
exhausted. Since the incremental amount is defined as a percent, the percent is calculated
as a constant number based on the initial (or original) capacity (25% of 10000 is 2500.)
To allow dynamic expansion for a detail data set, specify the maximum capacity and the
initial capacity when defining the data set. If dynamic expansion is not needed for the data
set, the maximum capacity is the only required parameter.
Verify that there is enough disk space for a data set to be expanded. Performance may be
impacted by the number of entries incremented when a detail data set is dynamically
expanded. The number of disk extents used for the data set file may also impact the
performance of TurboIMAGE/XL.
NOTE For existing databases, use DBChange Plus or a third-party utility to specify
the expansion parameters.
Master Key and Detail Search Items
The master key items and detail search items (also called critical items) that define a path
between two data sets must have identical type designators and simple sub-item lengths
when they are defined in the item part. The sub-item lengths must be simple because the
key and search items cannot be compound items. Because the same data item name can