— COMP9311 18s1 Lab 09 … query performance analysis
— Q1
explain analyze
select distinct s.sid
from CourseEnrolments e, Students s
where e.student=s.id and e.mark > 97;
QUERY PLAN
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Omitted
— Q2
explain
select s.code::text,s.name,t.year,t.sess::text,e.mark,e.grade::text,s.uoc
from Subjects s, Courses c, Terms t, CourseEnrolments e, Students st
where st.sid=2176435 and e.student = st.id and e.course = c.id
and c.subject = s.id and c.term = t.id
order by t.id,s.code;
QUERY PLAN
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Omitted
— Q3
explain
select p.name
from People p, CourseEnrolments e, Courses c, Subjects s, Terms t
where p.id = e.student and e.course = c.id and c.subject = s.id
and c.term = t.id and s.code like ‘COMP%’ and t.year = 2002;
QUERY PLAN
——————————————————————————————-
Omitted