sql server - Why is this SQL statement hanging when group by, sum, or where clause is included? -

i have sql statement:

select    t3.item1,    t3.item2,    sum(t1.moneys)    table t1 inner join table t2 on t1.key = t2.key inner join table t3 on t1.key2 = t3.key2    t2.type = 'thistype'    , t3.type2 = 'thistype' group    t3.item1, t3.item2 

if remove group by, sum, or where clause runs fine - if add of hangs forever... ideas... on sql server management studio 2008 r2

thanks

further testing

so created view:

select        t3.item1,        t3.item2,        t1.moneys,        t2.type,        t3.type2            table t1     inner join table t2 on t1.key = t2.key     inner join table t3 on t1.key2 = t3.key2 

and can select top 1000 view fine , see type want @ in data, when add 'where type2 = 'thistype'' hangs again...

your joining 3 tables millions of records, normal take bit run.

to answer question statistics, indices utilize retrieve records faster tables. without accurate or date statistics, indices can slow queries down.

http://blogs.technet.com/b/rob/archive/2008/05/16/sql-server-statistics.aspx