What is an Oracle Map Theme? Oracle Map Themes are also called Geometry Theme. A theme is a visual representation of a particular data layer. Using Oracle Map builder you can extract a GeoJSON from this Geometry theme. This geoJSON can be directly uploaded into Oracle Data Visualization as a custom map layer.
Oracle DB Map Theme for a sample of congressional districts (preview on Oracle Map Builder):
Extracted map layer rendered in Oracle Data Visualization Map:
Detailed steps on how to do this conversion can be found in this document
High level steps:
1) Install Oracle Map Builder(If not installed already).
2) Connect to the Database Schema where the maps/Spatial data is present
3) Select the table that contains Geometry Theme data
4) Use Map Builder tools to extract this geometry table in to geoJSON.