How To Improve The Efficience Of Sql Query ?

now i want to get results from server tables, but i found it is very slow, for example :

select Coalesce(T1.Name, T2.Name, T3.Name), T1.M1, T2.M2, T3.M3

from T1

full outer join T2

on Coalesce(T1.Name, NULL) = T2.Name

full outer join T3

on Coalesce(T1.Name, T2.Name) = T3.Name

in Tables i have builded index for name, but when every table have 20000 records, the sql above is very slow, is there other method to improve the query speed ?



Thks