Introduction to triggers

[This is preliminary documentation and is subject to change.]

This walkthrough will help you understand how a trigger is set on the data model elements to perform both sequential and state-based processing on data flow events.

Trigger setting

A trigger can be added:

Automatically during the mapping contruction when some predefined conditions are met.
By user, using:
- The mapping editor
- The data flow editors

Data flow events

A data flow event is a {event, operation, element} tuple.

Events	Operations	Elements
Enter Before After Leave	Select Insert Update Delete	Data source Data entity Data property

Triggering sequence

The pseudo-code extract triggering sequence is:

For each data source fire Enter extract phase triggers
For each data entity fire Enter extract phase triggers
For each record extracted
1. Fire Before select triggers for the data entity.
2. For each field in record
  1. Fire Before select triggers for the data property
  2. Fire After select triggers for the data property
3. Fire After select triggers for the data entity.
For each data entity fire Leave extract phase triggers
For each data source fire Leave extract phase triggers

Trigger list