Question

I’m building a report that collates a huge amount of data, the data for the report has taken shape as a view which runs in about 2 to 9 seconds (which is acceptable). I also have a function that returns a set of ids which needs to filter the view:

select *
from vw_report
where employee_id in (select id from dbo.fnc_security(@personRanAsID))

The security function on its own runs in less than a second. However when I combine the two as I have above the query takes over 15 minutes.

Both the view and the security function do quite a lot of work so originally I thought it might be down to locking, I’ve tried no lock on the security function but it made no difference.

Any tips or tricks as to where I may be going wrong?

It may be worth noting that when I copy the result of the function into the in part of the statement:

select *
from vw_report
where employee_id in (123, 456, 789)

The speed increases back to 2 to 9 seconds.

Answer 1

I ended up dumping the result from the security function into a temporary table and using the temporary table in my main query. Proved to be the fastest method.

e.g.:

create table #tempTable (id bigint)

select id 
into #tempTable
from dbo.fnc_security(@personRanAsID)

select *
from vw_report
where id in (select id from #tempTable)