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Population SSL
140 U929-J-Z125-9-76
5.2.2 Specifying the size of the set occurrences of a set
POPULATION IS integer
The size of the set occurrences must be specified in the following cases:
– if you want to store tables and member records in the proximity of the associated owner
records,
– if you want to facilitate subsequent table extensions,
– if you want to specify the size of a hash area for secondary keys in a SYSTEM set in
order to avoid overflow pages.
integer specifies an average set occurrence population. It should be the value which applies
to the majority of the set occurrences.
Based on this specification, UDS/SQL calculates:
– the storage space requirements for pointer arrays, lists, sort key tables and set
SEARCH key tables, provided the set is not a SYSTEM set,
– the storage space requirements for the member records of the set occurrences,
provided the set is not a SYSTEM set,
– the size of hash areas for secondary keys in a SYSTEM set.
UDS/SQL reserves the storage space calculated for a set occurrence in the next free space
following the owner record when storing the owner record.
The default value for integer is 0. In this case, no space is reserved for tables and member
records, and one page is reserved for each hash area.
Storage space requirements for pointer array, list, sort key table and set SEARCH key
table
Each of the above tables represents or contains all member records of a set occurrence.
Each member record corresponds to one line in the associated tables. This means that
integer specifies the number of lines in each table of the set occurrence.
Based on the number and the length of lines, UDS/SQL calculates the storage space
requirements for the tables.