Slow distinct query in SQL Server over large dataset

Question

We\'re using SQL Server 2005 to track a fair amount of constantly incoming data (5-15 updates per second). We noticed after it has been in production for a couple months that on

Answer 1

An indexed view can make this faster.

create view alltypes
with schemabinding as
select typename, count_big(*) as kount
from dbo.types
group by typename

create unique clustered index idx
on alltypes (typename)

The work to keep the view up to date on each change to the base table should be moderate (depending on your application, of course -- my point is that it doesn't have to scan the whole table each time or do anything insanely expensive like that.)

Alternatively you could make a small table holding all values:

select distinct typename
into alltypes
from types

alter table alltypes
add primary key (typename)

alter table types add foreign key (typename) references alltypes

The foreign key will make sure that all values used appear in the parent alltypes table. The trouble is in ensuring that alltypes does not contain values not used in the child types table.