combine Two different database tables(oracle and Mariadb) in an appian record

We have two separate databases: a legacy one (Oracle) and a current one (MariaDB). We do not want to import the legacy data into the current database. However, our customer wants to be able to search records across both databases.

The requirement is to connect both databases to our current application and build a search interface on a single page. There is no relationship between the two databases; the cases exist independently in each database and need to be merged for the search.

Is there a way to connect both schemas and build a unified search interface? How can we solve this problem using Appian?