Postgresql date range query with year and week number - postgresql

Question

Hi I would like to store the number of working hours for a given week in a table with,
hours, year, week
so I can aggregate the hours for a week quickly, where week is the ISO week number.
I then want to do a date range filter query on this table, let's say
From 2018-12-24 to 2019-01-21 (year 2018 week 52 to 2019 week 4).
If the user pass the year and week, then I would need to do a range check on a compound index where you compare the year value first, and then the week number.
How should I structure the query and index to efficiently retrieve records with this range?
This is a basic attempt, given a start year and start week, and an end year and end week:
select year, week, hours
from
weekly hours
where((year = 2018 and week >= 52) OR year > 2018) AND
((year = 2019 and week <=3) OR year < 2019)

Answer 1

You can compare more than one column with the <= or >= operator:
select *
from weekly_hours
where (year, week) >= (2018,52)
and (year, week) <= (2019,3);
That query can make use of an index on both columns, e.g.
create index on weekly_hours (year, week);

Answer 2

You can calculate the week as an absolute number and use this for your range queries. An expression index can be used for the absolute week calculation.
create table weekly_hours (
year int,
week int,
hours int
);
insert into weekly_hours
(year, week, hours)
values
(2018, 52, 10),
(2019, 4, 9),
(2019, 10, 9);
-- expression index that generates the absolute week
create index weekly_hours_absweek_idx on weekly_hours((year * 53 + week));
-- range query
select year, week, hours
from weekly_hours
where
year * 53 + week >= 2018 * 53 + 52
and year * 53 + week <= 2019 * 53 + 4;