Another point is that persist() while having other issues does not require an early flush to the db as the id is not returned.

I did forget to read HSEARCH-1270 and I see it as a valid use case. But it seems to be a cheap workaround for the lack of index transactions. We could make clear() work in such a way that solves the user problem or make clear() work consistently with the ORM notion (i.e. what is flushed is flushed and reduce my memory consumption).

There is no obvious winner it seems.