iX V6.5 (30391-90011)

Chapter 8 379

Using the Database Utilities

Restructuring the Database with TurboIMAGE/XL Utilities

• Removing data items from the original end of a data entry deﬁnition.

• Changing an automatic master to a manual master or vice versa.

• Adding or deleting a data set at the end of a schema.

• Changing the native language deﬁnition for the database.

These are unsupported schema changes. DBLOAD does not prohibit these changes; however,

the data is not guaranteed to be consistent. A change must be judged in light of the

particular database and the functioning of DBUNLOAD and DBLOAD, described later in this

chapter.

Basically, all entries from an old data set are put into the corresponding new data set,

except that no entries are directly put into automatic masters. The entries are truncated or

padded with binary zeros as necessary to ﬁt the entry length of the new data set. DBUNLOAD

and DBLOAD always handle full entries, without regard to item positions or lengths. If the

new data set entry is deﬁned with the items in a different order than the old data set,

DBLOAD may not fail but the data set entries, nevertheless, will be invalid. For example,

data of type real may now occupy the position of a character type item.

The number of the data set is determined by the order in which the data sets we re entered

in the schema ﬁle. Therefore, because data sets are loaded by number, additions and

deletions should be made at the end of the schema. Data set one would correspond with the

ﬁrst data set appearing in the schema. DBLOAD always returns a warning if it detects a

discrepancy between the number of data sets deﬁned in the schema and the number of

data sets on the DBLOAD media, but you can allow DBLOAD to continue after the warning if

you are conﬁdent that the database will not be corrupted.

In some circumstances, the load completes, but data is lost. For example, data is lost if the

capacity of a data set is reduced in the new database to less than the number of data set

entries on the tape. If this is not desired, increase the capacity of the data base and restart

the DBLOAD process (refer to "Restructuring the Database with TurboIMAGE/XL Utilities"

earlier in this chapter.)