CC error -DatabaseFailure, insufficient heap memory to allocate

Hi CC experts,

This is regarding sizing, we are working with 32GB, where we have allocated 7GB to our updater and rest of the size parameters are updated according to it .now we are getting error "Data base problem occur", Issue code : Database failure, Internal message : there is insufficient memory to allocate 163804. Please increase configuration parameter "heap memeory per user or try again". Can you please help me to understand

1.what is the best and efficient way to size and utilize maximum of it?

2. How can we purge the subscriber data for certain duration, will it free some GB?