List all tables in your database - largest first - largest by no of relpages

SELECT 

n.nspname AS schemaname, 

c.relname AS tablename,

c.relpages,

c. reltuples,  

pg_get_userbyid(c.relowner) AS tableowner, 

t.spcname AS tablespace, 

c.relhasindex AS hasindexes, 

c.relhasrules AS hasrules, 

c.reltriggers > 0 AS hastriggers

FROM pg_class c

LEFT JOIN pg_namespace n ON n.oid = c.relnamespace

LEFT JOIN pg_tablespace t ON t.oid = c.reltablespace

WHERE c.relkind = 'r'::"char"

order by c.relpages desc;