does existsByid Query includes limit 1?

Question

i tried use existsByid

@GetMapping("/{memberId}")
    public boolean getMember(@PathVariable("memberId") long memberId) {
        return memberRepository.existsById(memberId);
    }

and jpa send query like this

    select
        m1_0.member_id 
    from
        member m1_0 
    where
        m1_0.member_id=? 

it doesn't show limit 1 so I declared the method using a custom JPQL Query with @Query like this and sent the Query

    @Query()
    boolean existsByMemberId(long memberId);


    @GetMapping("/{memberId}")
    public boolean getMember(@PathVariable("memberId") long memberId) {
        return memberRepository.existsById(memberId);
    }

and then query included limit 1

 select
        m1_0.member_id 
    from
        member m1_0 
    where
        m1_0.member_id=? 
    limit
        ?

so I just wonderd existsById include limit 1 but doesn't show in the query or doesn't include limit 1

Answer 1

It looks like a side-effect of overriding/declaring CRUD repository methods.

Either way, limit 1 is pointless for simple existsBy... methods.

These methods are transformed to SQL select count()... queries, which without group by always return 1 and only 1 row.