Structure of pages Data page
U929-J-Z125-9-76 217
Dokuschablonen 19x24 Version 7.3us für FrameMaker V7.x vom 14.02.2007 © cognitas GmbH 2001-2007 18. Oktober 2007 Stand 11:29.50 Pfad: G:\vogt\fsc\ud s\Manuale\en\udsent_e\uds ent.k07
Meanings of bytes 1-28 or 1-32
There is a page index entry for each record and each table in the page, indicating the
position of the record or table. In the case of lists, there is a page index entry for the list itself
and for every record contained in it. The logical sequence of re cords in a list is not based
on their physical sequence, but on the sequence of the page index entries.
A data page must not contain two anchor records at the same time.
Byte Meaning
1-4 contains the address of the page.
13-16 specifies the length and the beginning of the free space. Since the free space
is filled with records and tables starting at the en d of the page, the beginning of
the free space borders on the last stored record or table.
This information on free place represents the second level of the UDS/SQL
three-level Free Place Administration facility.
17-18 contains the number of page index entries.
19-20 The page length may be 2048 bytes, 4000 bytes or 8096 bytes.
Record Table
21-24
or
21-28
Database key value of the record Database key value of the associated
owner record
25/29 DBTT column=0 DBTT column=1-n
26/30 Status=0: Record is not part of a list
(anchor record)
Status=2: Record is part of a list
Status=1
27-28
or
31-32
indicates the beginning of the record or table.
Table 19:Meanings of bytes 1-28 or 1-32 of a data page