During item views, it appears Hibernate is issuing database-modifying SQL during what should be a read-only request. It removes the item in question from collection2item, then re-adds it. Then it removes the collection from the community2collection table, and re-adds it.
While debugging a strange issue for a recent 6.0 deployment, I turned on Hibernate logging and noticed messages like the following occurring in the DSpace log for each item view request:
2017-05-17 10:09:31,893 DEBUG org.hibernate.SQL @ delete from public.collection2item where item_id=?
2017-05-17 10:09:31,982 DEBUG org.hibernate.SQL @ insert into public.collection2item (item_id, collection_id) values (?, ?)
2017-05-17 10:09:31,984 DEBUG org.hibernate.SQL @ delete from public.community2collection where collection_id=?
2017-05-17 10:09:31,991 DEBUG org.hibernate.SQL @ insert into public.community2collection (collection_id, community_id) values (?, ?)
To reproduce, install latest dspace-6_x branch, make sure the following are in your log4j.properties:
...and view an item page. If you grep dspace's log for "insert into" or "delete from", you will see some messages like the above on each item page view.