...
2. Update the metadata by user enroll Api for last read content idcontent state update Api
3. Migration on old user_enrolments records data migration for new column needed using user_content_comsumption table
...
API might become slower as we connect to multiple tables.
Conclusion
The last time access collection to be implemented by adding a new column (option 1). No migration is required as update user content state API is frequently called.