EXPLAIN select supp_nation, cust_nation, l_year, sum(volume) as revenue from ( select n1.n_name as supp_nation, n2.n_name as cust_nation, extract(year from l_shipdate) as l_year, l_extendedprice * (1 - l_discount) as volume from supplier, lineitem, orders, customer, nation n1, nation n2 where s_suppkey = l_suppkey and o_orderkey = l_orderkey and c_custkey = o_custkey and s_nationkey = n1.n_nationkey and c_nationkey = n2.n_nationkey and ( (n1.n_name = 'ARGENTINA' and n2.n_name = 'ETHIOPIA') or (n1.n_name = 'ETHIOPIA' and n2.n_name = 'ARGENTINA') ) and l_shipdate between date '1995-01-01' and date '1996-12-31' ) as shipping group by supp_nation, cust_nation, l_year order by supp_nation, cust_nation, l_year;
                            plan                             
-------------------------------------------------------------
                            sort                            
                                                            
                           groupby                          
                                                            
                             map                            
                                                            
                            join                            
                            hash                            
                                                            
 tablescan                       join                       
 supplier                        hash                       
                                                            
                            join                   tablescan
                            hash                   lineitem 
                                                            
                       join              tablescan          
                       hash              orders             
                                                            
                  join         tablescan                    
                  bnl          customer                     
                                                            
           tablescan tablescan                              
           nation    nation                                 
(23 rows)