For this query to be quick you need all keys, ie primary and foreign.
Does you tpch-h schema include those?

Niels

Yes, I have correctly set up the database schema. The population parameter was set to 1 during table initialization. The strange thing is that the other tested queries are executed as expected. i suspect that this is an optimization problem, as if we look at the query:

select
         n_name,
         sum(l_extendedprice * (1 - l_discount)) as revenue
from
         customer,
         orders,
         lineitem,
         supplier,
         nation,
         region
where
         c_custkey = o_custkey
         and l_orderkey = o_orderkey
         and l_suppkey = s_suppkey
         and c_nationkey = s_nationkey
         and s_nationkey = n_nationkey
         and n_regionkey = r_regionkey
         and r_name = 'ASIA'
         and o_orderdate >= date '1994-01-01'
         and o_orderdate < date '1994-01-01' + interval '1' year
group by
         n_name
order by
         revenue desc;

, there is a chain among the joined tables, as supplier joins with nation and lineitem, while lineitem joins with customer and customer joins with supplier again. So, if the firstly executed join is customer with supplier on nationkey, the result will be much bigger than the main memory capacity. Still, the selection predicates on tables orders make joining first orders with lineitem and then the result with customer a more reasonable choice, with much smaller needs in memory.
I have also attached the EXPLAIN output. Could that be the case?

Thanks.