Filter
Top Products
Introduction SSL
132 U929-J-Z125-9-76
Structure of a database key value
To find the physical address of records and associated tables, UDS/SQL can always make
use of an additional identifier, the database key value, which never changes during the life
of a record in the database.
A record type consists of a number of records which are consecutively numbered. The
record types are also numbered. The record sequence number (RSQ) and record type
reference (REC-REF) are combined to form the database key value of the record.
The database key is thus an identifier that uniquely identifies each record contained in the
database.
The structure of the database key value varies, depending on whether the database page
length is 2048 bytes or 4000/8096 bytes.
Figure 28: Structure of a database key value if the page length is 2048 bytes
Figure 29: Structure of a database key value if the page length is 4000 or 8096 bytes
The following applies to the value range for a record reference number (REC-REF):
–1 ≤ REC-REF ≤ 254 for databases with a 2048-byte page length
–1 ≤ REC-REF ≤ 2
15
-1 for databases with a 4000/8096-byte page length
1 byte
3 bytes
REC-REF RSQ
REC-REF
RSQ
= Record reference no.
= Record sequence no.
2 bytes
2 bytes
REC-REF
RSQ
REC-REF
RSQ
= Record reference no.
= Record sequence no.
not used
4 bytes