Developing an Open Source application with the contribution of many individuals over the internet is no easy task due to the challenges in communication. Creating a database schema that can be used by contributors physically apart and developing on different modules is no simple task either.

New data requirements need to be added to the data model with a thorough understanding about the dependencies that exist to this new data. Most of the time, the new data needed already exists in the database in different formats, therefore the existing data model should be carefully analyzed before making change.

Below is a entity relationship diagram of Sahana that can be used to visually understand about the Sahana database structure.

The Entity Relationship diagram for Sahana revision 1.79.2.4

First thing to notice in the database is that, there are tables with and without relationships defined. The lack of relationships can make it harder for new contributors of Sahana to learn about the database structure, making it harder to make improvements in the existing modules. Another importance for the need of relationships is to ensure database consistency.

Ones all the relationships are defined, it should be possible to explore if any improvements to the database can be done.