OWNER clause and SEARCH KEY clause Schema DDL
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hash-routine denotes the name of a module converting the secondary key to a 4-byte binary
number. This binary number is subsequently converted into a relative page number by
UDS/SQL. The corresponding page contains the pointer to the record (see page 213).
If hash-routine is omitted, UDS/SQL uses the same standard hash routine as for conversion
of the primary key on record type level (for programming a hash routine as well as using the
standard hash routine, see page 87).
More than one secondary key may be defined.
4.8.2 Dynamic set
In general, DML statements process one record of the database at a time.
One particular DML retrieval statement, however, selects several records from the database
at the same time (see the “Application Programming“ manual, FIND 7). The selected
records are buffered for further processing. UDS/SQL does this by automatic ally making the
records member records in a dynamic set.
It is characteristic of a dynamic set that, during a transac tion, it can accept records of
various record types, identifying them as intermed iate results of a search query, and discard
them when the intermediate result is no longer re quired. Membership in a dynamic set is
thus of the OPTIONAL MANUAL type and there is no defined member record type.
One set occurrence is sufficient for storing selected record s in a dynamic set as connection
data relating to certain owner records need not be stored, i.e. a dyna mic set is declared as
SYSTEM set.
The set is called dynamic because it holds member r ecords for the course of one trans-
action only. There is no static set membership.
In order to be able to define a dynamic set, the user must include a temporary realm in the
schema. The dynamic set is defined as follows:
SET NAME IS set-name
SET IS DYNAMIC
ORDER IS IMMATERIAL
OWNER IS SYSTEM.
If the Interactive Query Language IQL is to be used, the user mus t define eight dynamic
sets with the names IQL-DYN1 through IQL-DYN8. More details can be found in the manual
“Interactive Query System IQS“.