SQL文1：

SELECT relname, reltuples, (relpages / 128) as mbytes, (relpages * 8192.0 / (reltuples + 1e-10)) as average_row_size FROM pg_class ORDER BY mbytes DESC;

SQL文2：

SELECT pgn.nspname, relname, pg_size_pretty(relpages::bigint * 8 * 1024) AS size, CASE WHEN relkind = 't' THEN (SELECT pgd.relname FROM pg_class pgd WHERE pgd.reltoastrelid = pg.oid) WHEN nspname = 'pg_toast' AND relkind = 'i' THEN (SELECT pgt.relname FROM pg_class pgt WHERE SUBSTRING(pgt.relname FROM 10) = REPLACE(SUBSTRING(pg.relname FROM 10), '_index', '')) ELSE (SELECT pgc.relname FROM pg_class pgc WHERE pg.reltoastrelid = pgc.oid) END::varchar AS refrelname, CASE WHEN nspname = 'pg_toast' AND relkind = 'i' THEN (SELECT pgts.relname FROM pg_class pgts WHERE pgts.reltoastrelid = (SELECT pgt.oid FROM pg_class pgt WHERE SUBSTRING(pgt.relname FROM 10) = REPLACE(SUBSTRING(pg.relname FROM 10), '_index', ''))) END AS relidxrefrelname, relfilenode, relkind, reltuples::bigint, relpages FROM pg_class pg, pg_namespace pgn WHERE pg.relnamespace = pgn.oid AND pgn.nspname NOT IN ('information_schema', 'pg_catalog') ORDER BY relpages DESC;