Why are interface projections much slower than constructor projections and entity projections in Spring Data JPA with Hibernate?

Question

I\'ve been wondering which kind of projections should I use, so I did a little test, which covered 5 types of projections (based on docs: https://docs.spring.io/spring-data/

Answer 1

I experienced similar behavior with an older version of Spring Data and this was my take on it: https://blog.arnoldgalovics.com/how-much-projections-can-help/

I had a talk with Oliver Gierke (Spring Data lead) and he made some improvements (that's why you get so "good" results :-) ) but basically there will be always a cost on having abstractions vs coding it manually.

This is a trade-off as everything else is. On one hand you got flexibility, easier development, less maintenance (hopefully), on the other hand you get full control, a bit uglier query model.