refresh() vs clear()

Both sound like they undo something. They undo completely different things, on completely different scopes.

text

before refresh, in-memory status = open
after refresh(), in-memory status = modified-directly

before clear(), contains? true
after clear(), contains? false

run in a container — refresh() reloaded one entity; clear() detached everything without touching the database

refresh() vs clear()
Compared on	refresh()	clear()
Scope	One entity	Every managed entity
Touches the database?	Yes — issues a fresh SELECT	No
What happens to unsaved local changes	Discarded, overwritten by the database's real values	Kept in memory, but no longer tracked or ever going to be saved

refresh() is for one specific worry: "has this row changed underneath me?" — it reloads and overwrites whatever local changes existed. clear() is for a different one entirely — detaching everything at once, usually to stop a long-running batch operation from accumulating an ever-growing persistence context in memory. Reach for refresh() to get current data; reach for clear() to stop tracking, not to get anything.