these are undocumented for a reason as they will affect performance and
you will break your sql production server if you use them! they are *really* helpful for simulations for query plan analysis without having large amounts of data though.
original article hererock on with this cool code sample from above link:
use tempdb
go
create table t1(i int, j int)
go
create table t2(h int, k int)
go
set statistics profile on
go
select distinct(i) from t1
go
select * from t1, t2 where i = k order by j + k
go
update statistics t1 with rowcount = 10000, pagecount = 10000
update statistics t2 with rowcount = 100000, pagecount = 100000
go
select distinct(i) from t1 option (recompile)
go
select * from t1, t2 where i = k order by j + k option (recompile)
go
(via
don't feed the penguins)