截断后的pg_catalog.pg_class.relfilenode

Question

我有一个依赖于表的视图: create view hello_v as select * from hello；要从视图名称中检索被引用的表名，我认为pg_class和pg_depend表可能会很有用。对表进行截断会导致pg_depend中没有条目。

如何返回等于pg_catalog.relfilenode的pg_depend.refobjid？

我可以重复我的观点：

select version();

create table hello(name text);
create view hello_v as select * from hello;

select c.relname, c.relfilenode from pg_catalog.pg_class c inner join pg_catalog.pg_depend d on d.refobjid = c.relfilenode
    where c.relname in ('hello', 'hello_v') group by relname, relfilenode order by c.relname;

 relname | relfilenode
---------+-------------
 hello   |      305818
 hello_v |      305824

truncate hello;

select c.relname, c.relfilenode from pg_catalog.pg_class c inner join pg_catalog.pg_depend d on d.refobjid = c.relfilenode
    where c.relname in ('hello', 'hello_v') group by relname, relfilenode order by c.relname;

 relname | relfilenode
---------+-------------
 hello_v |      305824

 -- I hope to exist a record where relname = hello and relfilenode = xxx

或者简单地说：

create table hello(name text);

select c.relname, c.relfilenode from pg_catalog.pg_class c inner join pg_catalog.pg_depend d on d.refobjid = c.relfilenode
    where c.relname = 'hello' group by relname, relfilenode order by c.relname;

truncate hello;

select c.relname, c.relfilenode from pg_catalog.pg_class c inner join pg_catalog.pg_depend d on d.refobjid = c.relfilenode
    where c.relname = 'hello' group by relname, relfilenode order by c.relname;

谢谢。

Answer 1

您的联接条件错误。你想加入的是c.oid，而不是relfilenode。

这将正确显示您的表：

select c.relname, c.relfilenode from pg_catalog.pg_class c inner join pg_catalog.pg_depend d on d.refobjid = c.oid
where c.relname = 'hello' group by relname, relfilenode order by c.relname;