cpu_index_tuple_cost	0.005
cpu_operator_cost	0.0025
cpu_tuple_cost	0.1
parallel_setup_cost	1000
parallel_tuple_cost	0.1
random_page_cost	0.11
seq_page_cost	0.1

alter table respondents alter project_id set STATISTICS -1;
alter table respondents alter project_id set (n_distinct = 0);

analyze respondents;

Nested Loop  (cost=1.83..345316810.01 rows=868625 width=220) (actual time=0.462..0.462 rows=0 loops=1)
  ->  Nested Loop  (cost=1.13..16513.65 rows=16168 width=8) (actual time=0.431..0.445 rows=9 loops=1)
        ->  Index Only Scan using ix_respondents_projectid_id on respondents r  (cost=0.56..1405.48 rows=12858 width=8) (actual time=0.401..0.403 rows=9 loops=1)
              Index Cond: (project_id = 6)
              Heap Fetches: 0
        ->  Index Only Scan using ix_interviews_respondentid_id on interviews i  (cost=0.56..0.98 rows=2 width=16) (actual time=0.004..0.004 rows=1 loops=9)
              Index Cond: (respondent_id = r.id)
              Heap Fetches: 0
  ->  Index Scan using ix_interviewquestiondetails_interviewid_questionnumber on interview_question_details iqd  (cost=0.70..12977.02 rows=83800 width=220) (actual time=0.002..0.002 rows=0 loops=9)
        Index Cond: (interview_id = i.id)
Planning time: 2.900 ms
Execution time: 0.530 ms