Schemaball is a flexible schema visualizer for SQL databases. The purpose of Schemaball is to help visualize the relationships between tables. Tables are related by foreign keys, which are fields which store the value of a record field from another table. Foreign keys create a lookup relationship between two tables. Large schemas can have hundreds of tables and table relationships. Keeping track of them call can be tedious, error-prone and slow down the schema development process. Schemaball provides a means to create flexible, static graphic images of a schema. Tables and table links can be hidden, highlighted and foreign key relationships can be traversed forward or backward to highlight connected tables.
Schemaball produces images called schema balls. Schema balls are schema visualizations in which tables are ordered along a circle with table relationships drawn as curves or straight lines. Using an input configuration file, all elements of the schema ball can be configured.
Schemaball is free software, licensed under GPL. It is written in Perl and requires a few CPAN modules to run. It's simple to use, while being able to produce high quality schema balls suitable for publication. In particular, you can use Schemaball to generate elements of a schema ball and then create a composite in an image editing program. One such result is shown in the figure at right.
I am not longer actively working on Schemaball. As a prototype system, it works well to quickly figure out the extent of connectedness between tables and create some visually appealing images.
Schemaball was published in SysAdmin Magazine (Krzywinski, M. Schemaball: A New Spin on Database Visualization (2004) Sysadmin Magazine Vol 13 Issue 08).
I've since been using the circular composition form in my Circos project, which applies this layout to visualizing genomes (Circos is particularly popular in the field of comparative genomes, in which relationships between two or more genomes are analyzed and displayed).