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Structure of pages DBTT pages
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7.4.2 DBTT page
This section describes the layout of a DBTT page and the structure of the DBTT entries in
terms of lines and columns. There is precisely one DBTT line for each record of a record
type.
In the case of record types which are not owner record types, the DBTT consists of only
column 0, which contains the act-keys of the records.
Otherwise, one column each is added for every reference to
– a pointer array (MODE IS POINTER-ARRAY),
– a list (MODE IS LIST),
– a sort key table (MODE IS CHAIN, ORDER IS SORTED INDEXED), and
– an indexed set SEARCH key table.
UDS/SQL uses the DBTT line length and the database key value specifying the line in the
DBTT, together with the block number of the associated DBTT component, DBTT base or
DBTT extent to calculate the location of the associated DBTT line.
Depending on which page length was defined for the database, the length of a DBTT page
may be 2048 bytes, 4000 bytes or 8096 bytes.