/* Calculates your cache hit rate for reading tables */
SELECT
relname AS name, heap_blks_hit AS buffer_hits, heap_blks_read AS block_reads, heap_blks_hit + heap_blks_read AS total_read, CASE (heap_blks_hit + heap_blks_read)::float WHEN 0 THEN 'Insufficient data' ELSE (heap_blks_hit / (heap_blks_hit + heap_blks_read)::float)::text END ratio
FROM
pg_statio_user_tables
ORDER BY
heap_blks_hit / (heap_blks_hit + heap_blks_read + 1)::float DESC;