可以参考下：

select relnamespace,relkind,relname from pg_class where relnamespace in (select oid from pg_namespace) and relkind='r' order by 1,2;
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postgres=# create schema test;
CREATE SCHEMA

postgres=# select 'test'::regnamespace::oid;
  oid   
--------
 247296
(1 row)

postgres=# select 247296::regnamespace;
 regnamespace 
--------------
 test
(1 row)
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