Composite - multiple databases

There are cases in which phisically distinct databases are logically connected. And we want access them together, using their relationships to analyse their data.

For example the orders are in a database, but the descriptions of the products referred by these orders are in a different database.

The reason why the tables are in distinct databases can be that:

• they are accessed by different microservices
• they are accessed by different systems
• they where designed for different purposes but still their data is logically connected.

DBTrarzan is a database browser that uses foreign keys to traverse the tables of a relational database. But it can also traverse the tables of these logically connected databases.

How can we do it? There are no foreign keys among tables of distinct databases. Let’s add them then!

After we have put all these databases together in a composite, we define virtual foreign keys between the tables of these distinct databases. They are displayed in DBTarzan as normal foreign keys, so it is just to select some rows and double-click the foreign keys as usual to go from one table the table of a different database.