How to configure postgresql-9.2 to know blk_write_time in pg_stat_database
configuration above is correct. Before viewing the blk_write_time, do a vacuum. If you still see a 0 try increasing the inserts from 2000 to say 1000000.

Step 5: 
vacuum;
Step 6:
select datname, blk_write_time from pg_stat_database;