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

Chapter 10 165
Technical Articles
IMAGE/SQL with TurboIMAGE/XL Enhancements
:Run DBUTIL.PUB.SYS
>SET database name [/maintword] BTREEMODE1=ON
If your database is new, you will need to add data. You are now ready to
perform B-Tree index searches. You can include the wildcard character
in your DBFIND argument and observe the results.
Scalability
Prior to this enhancement, the modification intrinsics, DBPUT,
DBDELETE, and DBUPDATE (Critical Item Update feature ON) were
serialized for the database. That is, only one such intrinsic could
execute at a time for the database. In order to scale with the high-end
machines, TurboIMAGE/XL is enhanced to increase the concurrency of
these modification intrinsics.
The increased concurrency is based strictly on the database design. The
database is internally grouped into independent SUB-DATABASES
based on the physical relationships of master and detail data sets.
Subsequently, the modification intrinsics can execute concurrently for
these independent subdatabases. The throughput is dependent on the
number of subdatabases, the more the better. The worst case is a
database with only one subdatabase, one detail linked to 16 masters.
The best case is when there are numerous stand-alone masters or
details.
To use this enhancement, your database must be activated to use the
Dependency Semaphore. To achieve this, the ENABLE and DISABLE
commands of DBUTIL introduce a new option, DSEM. The default for
DSEM is DISABLED.
New syntax
EN[ABLE] database name[/maintword] FOR DSEM
DI[SABLE] database name[/maintword] FOR DSEM
After enabling your database for DSEM, if you feel that your database
design cannot attain expected concurrency, you may DISABLE the
feature as there is some overhead when the database is enabled for
DSEM.