iX V6.5 (30391-90011)

480 Chapter10

Internal Structures and Techniques

Scalability

In the above diagram, the independent sub-databases are:

1. M1

2. D1

3. D2 and M2

4. D3 and M3

5. D4 and M3

6. D5, M4 and M5

7. D6, M5 and M6

There are several different scenarios when concurrent modiﬁcations can be in progress.

For example:

M1 at all times as there is no dependency.

D1 at all times as there is no dependency.

Other masters M2, M3, M4, M5, and M6 if the depending detail is not being modiﬁed.

Other details D2, D3 or D4, and D5 or D6. This is if the dependent master(s) are not

being modiﬁed. Note that both D3 and D4, or D5 and D6 cannot be

concurrently modiﬁed.

Based on this approach, the throughput is dependent on the number of sub-databases, the

more, the better. The worst case is a database which can be sub-divided into only one

sub-database. For example, one detail linked to 16 masters. The best case is when there

are several stand-alone masters or details.

With this approach, some databases may beneﬁt in throughput and some may not.

Therefore, by default, TurboIMAGE/XL continues to work the way it did in versions prior

to C.07.00.

To use this enhancement, your database must be activated to use the Dependency

Semaphore. To achieve this, use the option, DSEM, with the ENABLE command of DBUTIL.

The default for DSEM is DISABLED.

New syntax:

EN[ABLE] database name [/maint word] FOR DSEM

DI[SABLE] database name [/maint word] FOR DSEM

After enabling your database for DSEM, if you feel that your database cannot beneﬁt by

using this feature, you may DISABLE it.