Dabacon Tables

In the Dabacon schema we can define an attribute to be an indexed attribute. Indexed attributes go into a Dabacon table.

Tables consist of a list of key/value pairs. The key may be a string (ntable), integer (itable) or reference (ftable). The 'value' part of the pair is always the refno of the element having that attribute value, for example: internally a name table may look something like:

…..

Janet = 123/456

John = 321/543

Jonathon = 111/321

…

Thus for a given name, the corresponding element can rapidly be found without having to scan the entire Multiple DataBase (MDB).

The keys in a name table must be unique. Integer and reference tables may contain the same key many times, for example: internally a reference table may look like:

….

=123/456 =234/555

=123/456 =222/333

=123/456 =211/999

=123/458 =203/909

In the above table, element =123/456 has appeared in the table three times. This means that three different elements were all referencing =123/456 for this particular attribute. This is common, for example: catalogue references are reference tables, and for these there may be hundreds of elements referencing the same catalogue component. A further point worth noting with respect to tables:

• Each Database (DB) has its own table. The entries in that table are for 'values' in that DB. Thus for the above ftable, =234/555 etc must be in this DB. However =123/456, =123/458 may be in a different DB. Indeed there may well be further references to =123/458 from other DBs. Hence to find all references to =123/456 we need to check the tables in each opened DB.