iX V6.5 (30391-90011)

ManualsBrandsHP ManualsSoftwareMPE/iX 6.5 Operating System

72 Chapter3

Deﬁning a Database

Set Part

item name is the name of a data item deﬁned in the item part.

path count is an integer between 0 and 16, inclusive, which is used with the key item

only. It indicates the number of paths that will be established to various

detail data sets. Refer to chapter 2 for more information about paths. A

path count must be speciﬁed for one, and only one, item in the master set.

A zero path count can be used with a manual master data item to indicate

the key item. A manual master deﬁned in this way is not linked to any

detail data set. An automatic master has one item that must have a path

count greater than zero.

maximum capacity is the maximum number of entries the data set can contain: that is,

the data set's capacity. It must be less than or equal to 2

−1

(2,147,483,647) and is limited by the size of the entry as well as the

maximum size of an MPE/iX ﬁle, jumbo or non-jumbo.

For non-jumbo data sets, if the capacity expansion parameter, initial

capacity, is speciﬁed and is less (not zero) than the maximum capacity, the

data set is enabled for dynamic expansion. Note that specifying initial

capacity for a jumbo data set will generate an error. When enabled for

dynamic expansion, the maximum capacity is adjusted by

TurboIMAGE/XL to represent an even multiple of the blocking factor.

Otherwise, it remains unchanged.

blocking factor is the number of data set media records in one block. If a value is not

speciﬁed, it is calculated by DBSCHEMA.

initial capacity is the initial capacity for the data set, that is, the number of entries for

which space will be allocated and initialized when the data set is created.

This number must be between 1 and 2

−1 inclusive but must be less than

or equal to the maximum capacity. Specifying initial capacity for a jumbo

data set will generate an error. This parameter should be used to closely

approximate the current volume of data. If it is very low, there can be

frequent expansions leading to severe disk fragmentation. If it is very

high, DBPUT may take a long time to complete which could impact other

database users. The initial capacity is adjusted to represent an even

multiple of the blocking factor. Initial capacity is an optional parameter. If

initial capacity is not speciﬁed, or if initial capacity is either zero or equal

to the maximum capacity, then dynamic capacity expansion is not enabled

for the data set, and maximum capacity is used for the data set ﬁle

creation.

increment is either the number of entries or the percentage of the initial capacity by

which the data set will be expanded each time its initialized space is

exhausted. If a percentage is used, the percent sign (%) must follow the

incremental amount. This increment parameter can only be used if the

initial capacity parameter is also speciﬁed. This number must be 1 to

32767 inclusive for percent, or 1 to 2

−1 (2,147,483,647) inclusive for

number of entries. If it is very low, there can be frequent expansions

leading to severe disk fragmentation. If it is very high, DBPUT may take a

long time to complete which could impact other database users.