Structure of records and tables Table structure
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Explanation of figure 58:
The length of the entries for the record sequence number (RSQ) and page index depend
on the page length that was defined for the database:
– In tables of a database with a 2048-byte page length, the RSQ entr y is 3 bytes long,
and the page index entry is 8 bytes.
– In tables of a database with a 4000-byte or 8096-byte page length, the RSQ entr y is
6 bytes long, and the page index entry is 12 bytes.
Pointer arrays, lists, sort key tables and standard SEARCH key tables are structured
according to the principle shown in figure 58. (The re presentation of the table line does not
apply to duplicates tables.) They are always stored in data pages. If a table does not fill a
page completely, the remaining space can be used for records or further tables. The table
headers contain the space reservations specified in the POPULATION clauses. This repre-
sents the third level of the three-level UDS/SQL Free Place Administration facility.
Furthermore, the table header contains pointers to other table par ts if the table exceeds one
page and a pointer to the next higher table level if the page belongs to a lower level. Two
further indicators show the table level of the page itself and the type of the ta ble.
1) follows the last table line in the case of lists.
2) bit 27=1 : list
26=1: multi-level table
25=1: table ATTACHED TO OWNER
24=1: duplicates table
3) does not apply to duplicates tables (see figure 60 and figure 61).
4) applies to the highest table page of a multi-level table or to the first table page of a
single-level table only.