criteria api - Prevent Hibernate N+1 Selects when grouping by an entity -

i have hibernate criteria object build thusly:

criteria obscriteria = hibernatetemplate.getsessionfactory()   .getcurrentsession().createcriteria(observation.class);  projectionlist projection = projections.projectionlist()   .add(projections.rowcount())   .add(projections.avg("value").as("avgscore"))   .add(projections.avg("type.score"))   .add(projections.max("date"))   .add(projections.groupproperty("observedsubject")); criteria.setprojection(projection); 

this produces correct result me, "observedsubject" property entity. when set set show_sql true, saw after first query (which returned 18 rows) there 18 selects observedsubject entities. i've tried:

criteria.setfetchmode("observedsubject", fetchmode.join); 

but didn't work. kind of stab in dark, tried:

criteria.createalias("observedsubject", "observedsubject", criteria.full_join); 

but didn't work, either. there way prevent behavior?

did annotate observedsubject fetchtype.lazy? if not, hibernate reverting default behavior, eager fetching.

if do want child association fetched @ runtime, don't want separate select calls each association, set @batchsize on association , hibernate batch select calls, making things more efficient.