Filter
Top Products
Realm concept Schema DDL
110 U929-J-Z125-9-76
4.10.2 Defining allocation of records to realms
RECORD NAME IS record-name
WITHIN realm-name-1[,realm-name-2,... AREA-ID IS identifier]
The allocation of data to realms and the placement of data within realms is performed
mainly when defining the physical storage structure by means of SSL (see the section
“Defining the placement of member records, tables and hash areas” on page 160). The
allocation of records to realms is however defined by means of the schema DDL.
realm-name-1, etc. specifies all the realms to contain records of the record type record-name.
If you specify multiple realms, you cannot insert any new records of this record type with
SQL.
identifier must be specified only if more than one realm name is specified.
identifier is specified by the user to denote the name of an item that is automatically
generated by UDS/SQL to store one of the specified realm names in each case. Prior to
storing a record, the database programmer must provide this item with the name of the
realm that is to contain the record (see the “Application Programming” manual, STORE).
The time required for retrieving member records via their set relationship can be decreased
by storing the member records in the same realm as the associated owner record. This
allows further placement optimization for records by means of SSL (see the section
“Placement within a realm” on page 163).
4.10.3 Temporary realms
AREA IS TEMPORARY
A temporary realm must be defined if the schema description contains dynamic sets or if
UDS/SQL must automatically generate a dynamic set because a specific DML statement
has been given (see the “Application Programming” manual, FIND 7). The temporary realm
serves to store the table that represents the set occurrence of the dynamic set and that
points to the associated member records.
A temporary realm must also be defined when you wish to access the database using SQL.