postgres=# select * from gp_dist_random('gp_id');  
  gpname   | numsegments | dbid | content   
-----------+-------------+------+---------  
 Greenplum |          -1 |   -1 |      -1  
 Greenplum |          -1 |   -1 |      -1  
 Greenplum |          -1 |   -1 |      -1  
 Greenplum |          -1 |   -1 |      -1  
 Greenplum |          -1 |   -1 |      -1  
 Greenplum |          -1 |   -1 |      -1  
 Greenplum |          -1 |   -1 |      -1  
 Greenplum |          -1 |   -1 |      -1  
 Greenplum |          -1 |   -1 |      -1  
 Greenplum |          -1 |   -1 |      -1  
……