Sandeep Gupta <gupta(dot)sandeep(at)gmail(dot)com> writes:
> details regarding buffer usage:
> [ 100% buffer hit rate ]
Your database is evidently fully cached in memory. If that's the
operating mode you expect, you need to change the planner's cost
parameters, in particular reduce random_page_cost to equal seq_page_cost.
There is plenty of material about this on the PG wiki or in the
pgsql-performance archives.
regards, tom lane