Oracle Single table with json vs set of tables using joins

I'm building a reporting solution. The data will be stored on Oracle database. I expect to get near to several billion data set since i have to keep data for 1 year period. When designing database schema i faced problem to go with single table or set of tables. 1. Single table in format of (ID, DATETTIME, JSON ) which has all the data dumped as json in JSON column. this will avoid any joins also cater for future event format changes. 2. Set of tables ( 4-6) data dived on them. query will be using several joins and several unions. Format will be hard to change. What would be the better approach in terms of performance. For large data set how efficient json over joins ?