Oracle query optimization help (involves TRUNC) - oracle

Question

Here is the query.
closed_ts is a timestamp column. What I am trying to do is, find out how many were "closed" today, this month, this year and this week. Is there a better way to do this?
select table_id,
case
when trunc(closed_ts) = trunc(SYSDATE, 'DD') then 1
else 0
end as day_count,
case
when trunc(closed_ts) >= trunc(SYSDATE, 'MM') then 1
else 0
end as month_count,
case
when trunc(closed_ts) >= trunc(sysdate, 'YYYY') then 1
else 0
end as year_count,
case
when trunc(closed_ts) >= TRUNC(sysdate, 'IW') then 1
else 0
end as week_count
from myTable

Answer 1

Seems like you would want to aggregate the values with a sum() around each case statement and group by table_id, but since you asked about query optimization...
If there is an index on closed_ts you won't be able to use it because you are trunc'ing it. Truncating the closed_ts date is unnecessary since you are checking whether it is strictly larger than day, week, month, year, so this query will definitely result in a full table scan.
I'd likely rewrite it without the trunc whether there was an index on closed_ts or not:
select table_id
,sum(case when closed_ts >= trunc(sysdate) then 1 else 0 end) as day_count
,sum(case when closed_ts >= trunc(sysdate,'MM') then 1 else 0 end) as month_count
,sum(case when closed_ts >= trunc(sysdate,'YYYY') then 1 else 0 end) as year_count
,sum(case when closed_ts >= trunc(sysdate,'IW') then 1 else 0 end) as week_count
from myTable
group by table_id
btw: table_id sounds like a primary or surrogate key - are you sure you want it in the results?

Answer 2

Pop an index on (closed_ts,table_id), and apply a predicate on closed_ts as below ...
select
table_id,
sum(case when closed_ts >= trunc(SYSDATE,'DD' ) then 1 end) day_count,
sum(case when closed_ts >= trunc(SYSDATE,'MM' ) then 1 end) month_count,
sum(case when closed_ts >= trunc(SYSDATE,'YYYY') then 1 end) year_count,
sum(case when closed_ts >= trunc(SYSDATE,'IW' ) then 1 end) week_count,
from
myTable
where
closed_ts >= least(trunc(SYSDATE,'YYYY'),trunc(SYSDATE,'IW'))
group by
table_id
As user1842757 mentioned, lose the trunc on the closed_ts. You can also lose the ELSE 0 in the case statements