pg_buffercache:we can look inside the current contents of the PostgreSQL shared_buffers database cache using the pg_buffercache module.we could look at how blocks in shared memory change as we perform various activities on the database using pg_buffercache.
psql -d <databasename> -U postgres
— Make sure contrib functionality is available before installing pg_buffercache
— Execute uniinstall pg_buffercache if a old version of pg_buffercache already exists
— \i /usr/pgsql-9.0/share/contrib/uninstall_pg_buffercache.sql