To not loop over the index of all subscribers all the time, I suggest introducing a lastChanged timestamp for every user, saved with the index, which will be updated erverytime a user uploads a new image.
This way we just need to check the timestamps, if anything changed.
To not loop over the index of all subscribers all the time, I suggest introducing a lastChanged timestamp for every user, saved with the index, which will be updated erverytime a user uploads a new image.
This way we just need to check the timestamps, if anything changed.