参考: https://www.postgresql.org/docs/9.3/catalog-pg-class.html

    执行sql

    1. select relkind,count(1),string_agg(relname,' ') from pg_class group by relkind

    看到

     relkind | count
---------+-------
 S       |     9
 r       |    94
 v       |   128
 i       |   193
 c       |     2
 t       |    60
(6 行记录)

    r = ordinary table, i = index, S = sequence, v = view, m = materialized view, c = composite type, t = TOAST table, f = foreign table
    分别对应 普通表, 索引, 视图, 物化视图, 自定义类型, toast表(pg内部隐藏表, 行外存储), 外键表(内部隐藏表)