Communicator 3000 MPE/iX Release 6.0 (Platform Software Release C.60.00) (30216-90269)

Chapter 10 159
Technical Articles
IMAGE/SQL with TurboIMAGE/XL Enhancements
When there is no room in the expanded area and cannot be expanded
further, however, there is room in the original area based on the free
entry count, the original area is scanned once again (long search) to
find a secondary address for the new entry. If a free entry is found,
the new entry resides there, and it becomes the last entry in the
synonym chain. Otherwise, the set is full and DBPUT will fail.
3. If the primary address is occupied by a secondary entry, the
secondary entry is relocated to another secondary address in either
the original area or the expansion area. A free entry is searched as
described in item 2 above. The new entry (primary) becomes a
synonym chain head with a count of one. TurboIMAGE/XL performs
synonym chain maintenance for the secondary entry which
relocates.
Following the expansion, TurboIMAGE/XL updates various fields
related to the expansion such as current capacity, including the
expansion, in the root file. Also, the data set user label is updated for
the last entry used in the file (high-water mark), free entry count, and
pointer to the put-delete chain head.
Intrinsics and utilities. The following intrinsics and utilities are
enhanced to support MDX:
• DBINFO modes 205 and 208 (new for MDX) give detailed
information pertaining to dynamic expansion. The buffer layout for
mode 205 remains the same as that of DDX except that it is relevant
to MDX. The buffer layout for new DBINFO mode 208 is in the
following table.
Buffer must be at least a 64-byte record and returns the
following (each element is a 32-bit word):
Element Contents
1 Primary (hashing) capacity for masters, 0 for details
2 Current capacity, including expansions
3 Maximum capacity
4 Expansion threshold:
-1 ... 100 percentage
-1 this value means expansion is not triggered by
percentage, or it is a non-expandable set.
5 Delete chain free head (0 for non-expanded masters)