TurboIMAGE/XL Database Management System Reference Manual MPE/iX V6.5 (30391-90011)

494 Chapter11
B-Tree Indices
Overview of B-Tree Indices
b. DBFIND modes with added functionality pertaining to B-Tree indices:
1 can continue to work as it does in releases prior to the release of
B-Tree index feature (C.07.00), despite the presence of a B-Tree
index, or it can be used for a B-Tree search if BTREEMODE1 is ON.
4 used for B-Tree index searches on numeric as well as ASCII types
and returns accurate chain (super-chain) counts. Requires a
structured argument.
10 allows you to simulate the DBFIND mode 1 in releases prior to the
release with B-tree index feature even when the item has a B-Tree
index (explicit or implicit), BTREEMODE1 is on, and the argument
contains a wildcard character. It returns accurate chain count. This
is the same as TPI mode 10. Requires a simple argument.
21 is the same as B-Tree index search using DBFIND mode 1, except it is
a faster version and does not return accurate chain counts. Requires
a simple argument.
24 is the same as B-Tree index search using DBFIND mode 4, except it is
a faster version and does not return accurate chain counts. Requires
a structured argument.
c. Allows wildcard search, as well as range search (< , <=, > , >=,"PK", or [ ] for
between).
d. If BTREEMODE1 is ON, DBFIND mode 1 of X or U type item having a B-Tree index
(explicit or implicit) and the argument containing a wildcard character will result in
a B-Tree index search.
e. For wildcard (generic) search, the wildcard should be the terminating character in
the argument. Characters beyond that will be ignored.
f. Status array reflects information based on data set, mode, and search type. B-Tree
index searches for modes 1 and 4 for details give super-chain (multiple detail chain)
counts and record numbers of first entry in first detail chain and last entry in last
detail chain.
• DBGET modes 5 and 6 can be used for B-Tree index retrieval for masters or details.
Super-chains are traversed for detail data sets.
• KSAM/iX files are used for B-Tree index files. These are KSAM related key points:
a. There is one KSAM/iX privileged file with a filecode of -412 for each B-Tree index file.
The size limit for this B-Tree index file is 4 Gbytes. A jumbo master (larger than 4
Gbytes) can have a B-Tree index file provided the B-Tree index file remains within
its 4 Gbyte limit.
b. KSAM/iX B-Tree index file is named using the POSIX file format with the "idx"
extension (lowercase). For example:
/ACTSALES/GRPSALES/ORDERS03.idx
c. KSAM/iX B-Tree index file records consist only of a single key, which is a duplicate of