Show Postgres buffer sizes

pg_buffercache_sizes.sql

CREATE EXTENSION pg_buffercache;

SELECT  c.relname,
        pg_size_pretty(count(*) * 8192) as buffered, round(100.0 * count(*) / (SELECT setting FROM pg_settings WHERE name='shared_buffers')::integer,1) AS buffers_percent,
        round(100.0 * count(*) * 8192 / pg_relation_size(c.oid),1) AS percent_of_relation,
        round(100.0 * count(*) * 8192 / pg_table_size(c.oid),1) AS percent_of_table
FROM    pg_class c
        INNER JOIN pg_buffercache b
            ON b.relfilenode = c.relfilenode
        INNER JOIN pg_database d
            ON (b.reldatabase = d.oid AND d.datname = current_database())
GROUP BY c.oid,c.relname
ORDER BY 3 DESC
LIMIT 10;