Writing DDL for Dad applications

Writing DDL (Adamo Data Definition Language) for Dad is basically not different from the DDL you write for normal Adamo applications. However there are some rules you should keep in mind if you are using the Dad updating mechnism.

As tables in the update mode need a time period of validity you need to add the following columns to all your updating tables and the keytables of dataflows which contain updating tables.

     iTimeStart = INTE               : 'start time of Validity',
     iTimeEnd   = INTE               : 'end time of Validity',
     iLocalId   = INTE   : 'Internal RowID'

Also it is wise to set up the update tables with respect to the update intervals which are expected. Data with short update intervals should be put into a (hopefully) small table whereas data with longer update intervals will be in another table. Another limitation to the DDL on the server side is the fact that servers can handle different dataflows only if tables do not appear in more than one dataflows and keytables must never be part of a dataflow.
This page is maintained by Wolfgang Wander.